Evaluation of salivary gland protein 1 antibodies in patients with primary and secondary Sjogren's syndrome

Clinical Significance of Uncommon, Non-Clinical, and Novel Autoantibodies

Autoantibodies are a common mark of autoimmune reaction and their identification in the patients' serum, cerebrospinal fluid, or tissues is generally believed to represent diagnostic or prognostic biomarkers of autoimmune diseases or autoinflammatory conditions. Traditionally, autoantibody testing is an important part of the clinical examination of suspected patients, and in the absence of reliable T cell tests, characterization of autoantibody responses might be suitable in finding causes of specific autoimmune responses, their strength, and sometimes commencement of autoimmune disease. Autoantibodies are also useful for prognostic stratification in clinically diverse groups of patients if checked repeatedly. Antibody discoveries are continuing, with important consequences for verifying autoimmune mechanisms, diagnostic feasibility, and clinical management. Adding newly identified autoantibody-autoantigen pairs to common clinical laboratory panels should help upgrade and harmonize the identification of systemic autoimmune rheumatic disorders and other autoimmune conditions. Herein, we aim to summarize our current knowledge of uncommon and novel autoantibodies in the context of discussing their validation, diagnostic practicability, and clinical relevance. The regular updates within the field are important and well justified.

Autoantibodies identify primary Sjögren's syndrome in patients lacking serum IgG specific for Ro/SS-A and La/SS-B

OBJECTIVE

Identify autoantibodies in anti-Ro/SS-A negative primary Sjögren's syndrome (SS).

METHODS

This is a proof-of-concept, case-control study of SS, healthy (HC) and other disease (OD) controls. A discovery dataset of plasma samples (n=30 SS, n=15 HC) was tested on human proteome arrays containing 19 500 proteins. A validation dataset of plasma and stimulated parotid saliva from additional SS cases (n=46 anti-Ro+, n=50 anti-Ro-), HC (n=42) and OD (n=54) was tested on custom arrays containing 74 proteins. For each protein, the mean+3 SD of the HC value defined the positivity threshold. Differences from HC were determined by Fisher's exact test and random forest machine learning using 2/3 of the validation dataset for training and 1/3 for testing. Applicability of the results was explored in an independent rheumatology practice cohort (n=38 Ro+, n=36 Ro-, n=10 HC). Relationships among antigens were explored using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) interactome analysis.

RESULTS

Ro+ SS parotid saliva contained autoantibodies binding to Ro60, Ro52, La/SS-B and muscarinic receptor 5. SS plasma contained 12 novel autoantibody specificities, 11 of which were detected in both the discovery and validation datasets. Binding to ≥1 of the novel antigens identified 54% of Ro- SS and 37% of Ro+ SS cases, with 100% specificity in both groups. Machine learning identified 30 novel specificities showing receiver operating characteristic area under the curve of 0.79 (95% CI 0.64 to 0.93) for identifying Ro- SS. Sera from Ro- cases of an independent cohort bound 17 of the non-canonical antigens. Antigenic targets in both Ro+ and Ro- SS were part of leukaemia cell, ubiquitin conjugation and antiviral defence pathways.

CONCLUSION

We identified antigenic targets of the autoantibody response in SS that may be useful for identifying up to half of Ro seronegative SS cases.

Not all autoantibodies are clinically relevant. Classic and novel autoantibodies in Sjögren’s syndrome: A critical review

Sjögren’s syndrome (SjS) is a heterogeneous systemic disease. The abnormal responses to La/SSB and Ro/SSA of both B-cells and T-cells are implicated as well as others, in the destruction of the epithelium of the exocrine glands, whose tissue characteristically shows a peri-epithelial lymphocytic infiltration that can vary from sicca syndrome to systemic disease and lymphoma. Despite the appearance of new autoantibodies, anti-Ro/SSA is still the only autoantibody included in the American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria and is used extensively as a traditional biomarker in clinical practice. The study and findings of new autoantibodies in SjS has risen in the previous decade, with a central role given to diagnosis and elucidating new aspects of SjS physiopathology, while raising the opportunity to establish clinical phenotypes with the goal of predicting long-term complications. In this paper, we critically review the classic and the novel autoantibodies in SjS, analyzing the methods employed for detection, the pathogenic role and the wide spectrum of clinical phenotypes.

The Diagnostic Performance of Early Sjögren's Syndrome Autoantibodies in Juvenile Sjögren's Syndrome: The University of Florida Pediatric Cohort Study

Objectives

The aim of this study was to evaluate the clinical validity of early Sjögren's syndrome (SS) autoantibodies (eSjA), which were originally marketed for early diagnosis of SS, for juvenile SS (JSS) in a recently identified pediatric cohort.

Methods

A total of 105 symptomatic subjects with eSjA results available were evaluated at the Center for Orphaned Autoimmune Disorders at the University of Florida and enrolled for this study. JSS diagnosis was based on the 2016 ACR/EULAR SS criteria. Demographic/clinical/laboratory parameters were compared between JSS (n = 27) and non-JSS (n = 78) for % positivity, sensitivity, and specificity of eSjA (SP1, anti-salivary protein; CA6, anti-carbonic anhydrase VI; PSP, anti-parotid secretory protein) and classic SS-autoantibodies (cSjA; ANA, SSA/SSB, RF, and others) either alone or in combination. Associations between eSjA and diagnostic/glandular parameters were also determined by Fisher's exact test.

Results

Compared to non-JSS, JSS patients exhibited sicca symptoms demonstrating reduced unstimulated salivary flow rate (USFR) and abnormal glandular features revealed by salivary gland ultrasound (SGUS). Among cSjA, ANA demonstrated the highest sensitivity of 69.2%, while SSA, SSB, and RF showed around 95% specificities for JSS diagnosis. The % positive-SSA was notably higher in JSS than non-JSS (56% vs. 5%). Of eSjA, anti-CA6 IgG was the most prevalent without differentiating JSS (37%) from non-JSS (32%). Sensitivity and specificity of eSjA were 55.6 and 26.9%, respectively. Autoantibodies with potentially applicable specificity/sensitivity for JSS were seen only in cSjA without a single eSjA included. There were no associations detected between eSjA and focus score (FS), USFR, SSA, SGUS, and parotitis/glandular swelling analyzed in the entire cohort, JSS, and non-JSS. However, a negative association between anti-PSP and parotitis/glandular swelling was found in a small group of positive-SSA (n = 19, p = 0.02) whereas no such association was found between anti-PSP-positive compared to anti-PSP-negative. JSS and non-JSS groups differed in FS, USFR, and EULAR SS Patient Reported Index Dryness/Mean in CA6/PSP/ANA, SP1, and SSA-positive groups, respectively. Additionally, a higher FS was found in RF-positive than RF-negative individuals.

Conclusions

eSjA underperformed cSjS in differentiating JSS from non-JSS. The discovery of clinical impact of eSjA on early diagnosis of JSS necessitates a longitudinal study.

Ocular Surface Biomarkers

ABSTRACT

Sjögren syndrome (SS) is a chronic inflammatory autoimmune disease of the lacrimal and salivary glands. Salivary gland biopsy is still one of the most valuable and acceptable diagnostic tests for SS, which however, is an invasive test. Therefore, noninvasive diagnostic biomarkers with high specificity and sensitivity are required for the diagnosis and assessment of SS. Because ophthalmological testing constitutes to an important part for the diagnosis of SS. Tears harbor biomarkers with a high potential to be used for differential diagnosis and assessment of treatment in many systemic disorders, including SS. This review aims to summarize recent advances in the identification of tear biomarkers of SS, trying to identify reliable, sensitive, and specific biomarkers that can be used to guide treatment decisions.

Epithelial-immune cell interplay in primary Sjögren syndrome salivary gland pathogenesis

In primary Sjögren syndrome (pSS), the function of the salivary glands is often considerably reduced. Multiple innate immune pathways are likely dysregulated in the salivary gland epithelium in pSS, including the nuclear factor-κB pathway, the inflammasome and interferon signalling. The ductal cells of the salivary gland in pSS are characteristically surrounded by a CD4⁺ T cell-rich and B cell-rich infiltrate, implying a degree of communication between epithelial cells and immune cells. B cell infiltrates within the ducts can initiate the development of lymphoepithelial lesions, including basal ductal cell hyperplasia. Vice versa, the epithelium provides chronic activation signals to the glandular B cell fraction. This continuous stimulation might ultimately drive the development of mucosa-associated lymphoid tissue lymphoma. This Review discusses changes in the cells of the salivary gland epithelium in pSS (including acinar, ductal and progenitor cells), and the proposed interplay of these cells with environmental stimuli and the immune system. Current therapeutic options are insufficient to address both lymphocytic infiltration and salivary gland dysfunction. Successful rescue of salivary gland function in pSS will probably demand a multimodal therapeutic approach and an appreciation of the complicity of the salivary gland epithelium in the development of pSS.

Association Between Early Sjögren Markers and Symptoms and Signs of Dry Eye

PURPOSE

Animal models suggest that early markers of Sjögren syndrome (EMS)-antibodies against salivary protein 1, parotid secretory protein, and carbonic anhydrase 6 (CA6)-are more accurate signals of early Sjögren when compared with classic markers (anti-Ro and anti-La). To further understand the relationship between EMS and dry eye (DE), we compared symptoms and signs of DE in subjects who tested positive versus negative for EMS.

METHODS

In this cross-sectional study, patients at the Miami Veterans Affairs Eye Clinic who were tested for EMS underwent a standard ocular surface examination. Indications for EMS testing included DE symptoms in combination with dry mouth symptoms, low tear production, corneal staining, or a Sjögren disease-associated autoimmune disease. Statistical tests performed were the χ test, Fisher exact test, independent sample t test, and Spearman correlation.

RESULTS

Seventy-three percent of 44 patients tested positive for 1 or more EMS. CA6 IgG was most frequently elevated, followed by CA6 IgM and parotid secretory protein IgG. EMS-positive versus EMS-negative subjects were more likely to escalate DE treatment past artificial tears to topical cyclosporine (n = 32, 100% vs. n = 9, 75%, P = 0.02). There were no demographic or comorbidity differences between EMS-positive and EMS-negative subjects, and marker levels did not correlate with more severe tear film measures.

CONCLUSIONS

Most of the individuals with DE tested positive for 1 or more EMS antibodies, including men and Hispanics. Future studies will be needed to understand how to incorporate EMS data into the care of an individual with DE.

Early diagnosis and treatment for Sjögren's syndrome: current challenges, redefined disease stages and future prospects

There are some challenges and unmet needs in the early diagnosis and management of Sjögren's syndrome (SjS) such as prominent glandular dysfunction at diagnosis and long diagnostic delay. Those challenges are partly attributed to the lack of a good knowledge of the early stages of SjS, which is a major obstacle to delivering appropriate care to SjS patients. Findings from both clinical and experimental studies suggest the plausibility of a redefined SjS course consisting of 4 stages, which includes initiation stage, preclinical stage, asymptomatic SjS stage and overt SjS stage. More studies focusing on the pathological processes and changes during the early stages of SjS are needed. To enable early diagnosis and treatment for SjS, more useful biomarkers of the early stages of SjS need to be identified, and individuals at high risk of SjS development need to be identified. Appropriate screening can be performed to facilitate the early diagnosis of SjS among those high-risk individuals.

An algorithm for the preoperative diagnosis and treatment of ocular surface disorders

Any ocular surface disease (OSD), but most commonly, dry-eye disease (DED), can reduce visual quality and quantity and adversely affect refractive measurements before keratorefractive and phacorefractive surgeries. In addition, ocular surgery can exacerbate or induce OSD, leading to worsened vision, increased symptoms, and overall dissatisfaction postoperatively. Although most respondents of the recent annual American Society of Cataract and Refractive Surgery (ASCRS) Clinical Survey recognized the importance of DED on surgical outcomes, many were unaware of the current guidelines and most were not using modern diagnostic tests and advanced treatments. To address these educational gaps, the ASCRS Cornea Clinical Committee developed a new consensus-based practical diagnostic OSD algorithm to aid surgeons in efficiently diagnosing and treating visually significant OSD before any form of refractive surgery is performed. By treating OSD preoperatively, postoperative visual outcomes and patient satisfaction can be significantly improved.

Prevalence of Novel Candidate Sjögren Syndrome Autoantibodies in the Penn Sjögren's International Collaborative Clinical Alliance Cohort

PURPOSE

To evaluate the prevalence of novel candidate autoantibodies associated with Sjögren syndrome (SS) and their ability to identify those with SS among participants with dry eye enrolled in the Sjögren's International Collaborative Clinical Alliance (SICCA) study at the University of Pennsylvania (Penn).

METHODS

All participants previously underwent a full ocular and systemic evaluation for possible SS as part of the SICCA study. An enzyme-linked immunosorbent assay was used to detect IgG, IgA, and IgM autoantibodies to salivary protein 1 (SP-1), parotid secretory protein (PSP), and carbonic anhydrase 6 from previously banked baseline serum samples from SICCA study participants enrolled at Penn. The prevalence rate of each autoantibody, calculated by considering the presence of any isotype as antibody positive, was compared between participants with dry eye with SS (n = 81) or without SS (n = 129) using the Fisher exact test.

RESULTS

The prevalence of SP-1 IgM autoantibodies was higher in those with SS compared with those without SS (14% vs. 5%; P = 0.03). Similarly, the prevalence of PSP IgA autoantibodies was higher in those with SS compared with non-SS dry eye participants (21% vs. 11%; P = 0.048). There was no statistically significant difference in the prevalence of carbonic anhydrase 6 autoantibodies between those with or without SS (15% vs. 20%; P = 0.36).

CONCLUSIONS

In the Penn SICCA cohort, SP-1 IgM and PSP IgA autoantibodies were more prevalent in the serum of SS-related dry eye participants compared with those without SS. Further longitudinal studies are needed to determine the clinical significance of these findings.

P2 Receptors as Therapeutic Targets in the Salivary Gland: From Physiology to Dysfunction

Although often overlooked in our daily lives, saliva performs a host of necessary physiological functions, including lubricating and protecting the oral cavity, facilitating taste sensation and digestion and maintaining tooth enamel. Therefore, salivary gland dysfunction and hyposalivation, often resulting from pathogenesis of the autoimmune disease Sjögren's syndrome or from radiotherapy of the head and neck region during cancer treatment, severely reduce the quality of life of afflicted patients and can lead to dental caries, periodontitis, digestive disorders, loss of taste and difficulty speaking. Since their initial discovery in the 1970s, P2 purinergic receptors for extracellular nucleotides, including ATP-gated ion channel P2X and G protein-coupled P2Y receptors, have been shown to mediate physiological processes in numerous tissues, including the salivary glands where P2 receptors represent a link between canonical and non-canonical saliva secretion. Additionally, extracellular nucleotides released during periods of cellular stress and inflammation act as a tissue alarmin to coordinate immunological and tissue repair responses through P2 receptor activation. Accordingly, P2 receptors have gained widespread clinical interest with agonists and antagonists either currently undergoing clinical trials or already approved for human use. Here, we review the contributions of P2 receptors to salivary gland function and describe their role in salivary gland dysfunction. We further consider their potential as therapeutic targets to promote physiological saliva flow, prevent salivary gland inflammation and enhance tissue regeneration.

Clair EW. Recent advances in the search for a targeted immunomodulatory therapy for primary Sjögren's syndrome

Primary Sjögren's syndrome is a chronic autoimmune disease characterized by salivary and lacrimal gland dysfunction, leading to substantial morbidity and reduced quality of life. Many patients with primary Sjögren's syndrome also have extraglandular systemic complications, some of which can be organ- or life-threatening. Over the last decade, numerous targeted immunomodulatory therapies for primary Sjögren's syndrome have failed to show a benefit in clinical trials, and as yet no disease-modifying therapy has been approved for this disease. Herein, we provide an updated review of the clinical trial landscape for primary Sjögren's syndrome and the numerous efforts to move the field forward, including the development of new classification criteria and outcome measures, the results of recent clinical trials in this field, the challenges faced in the search for effective therapies, and the expanding pipeline of novel therapies under development.

Profiling Autoantibodies against Salivary Proteins in Sicca Conditions

Salivary gland dysfunction occurs in several autoimmune and immune-related conditions, including Sjögren syndrome (SS); immune checkpoint inhibitor-induced sicca (ICIS) that develops in some cancer patients and is characterized by severe, sudden-onset dry mouth; and autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Although subjects with these conditions present with oral dryness and often exhibit inflammatory infiltration of the salivary gland, little is known about the B-cell humoral responses directed against salivary gland protein targets. In this study, autoantibodies were evaluated against Ro52, Ro60, and La, as well as against a panel of 22 proteins derived from the salivary proteome. The tested cohort included healthy volunteers and subjects with SS, ICIS, and APECED without and with sicca. As expected, a high percentage of autoantibody seropositivity was detected against Ro52, Ro60, and La in SS, but only a few ICIS patients were seropositive for these autoantigens. A few APECED subjects also harbored autoantibodies to Ro52 and La, but only Ro60 autoantibodies were weakly associated with a small subset of APECED patients with sicca. Additional testing of the salivary panel failed to detect seropositive autoantibodies against any of the salivary-enriched proteins in the SS and ICIS subjects. However, APECED subjects selectively demonstrated seropositivity against BPI fold containing family A member 1 (BPIFA1), BPI fold containing family A member 2 (BPIFA2)/parotid salivary protein (PSP), and lactoperoxidase, 3 salivary-enriched proteins. Moreover, high levels of serum autoantibodies against BPIFA1 and BPIFA2/PSP occurred in 30% and 67% of the APECED patients with sicca symptoms, respectively, and were associated with an earlier age onset of oral dryness (P = 0.001). These findings highlight the complexity of humoral responses in different sicca diseases and provide new insights and biomarkers for APECED-associated sicca (ClinicalTrials.gov: NCT00001196; NCT00001390; NCT01425892; NCT01386437).

Sjögren's syndrome and systemic lupus erythematosus: links and risks

Systemic lupus erythematosus (SLE) and Sjögren’s syndrome (SS) may coexist, and they are chronic complex disorders, with an autoimmune background, multifactorial etiology, multiple circulating autoantibodies, and variable prognosis. The prominent feature of SS is the impairment of the lacrimal and salivary glands leading to sicca symptoms. This disease may be classified as primary Sjögren’s syndrome (pSS), or secondary Sjögren’s syndrome (sSS) since it is often associated to other autoimmune disorders, principally SLE, rheumatoid arthritis, and systemic sclerosis. Systematic reviews and meta-analyses show an sSS prevalence in SLE patients of about 14%–17.8%. Herein, we updated important aspects of the clinical association between SLE and sSS through a narrative review of the PubMed database in the last 5 years (from July 2013 to October 2018) with the terms “Sjogren syndrome and systemic lupus erythematosus”. The following aspects are addressed: the classification criteria for sSS; differences and similarities between SLE and pSS regarding demographic, clinical, and serological characteristics (including new autoantibodies), as well as comorbidities; the etiopathogenic links between SLE and pSS (including genetic and environmental factors, B-cell activation, and autoantibodies); the predictive factors for sSS onset in SLE patients; the ocular and oral involvements due to sSS in SLE; and the main distinctive demographic, clinical, and serological features of SLE with and without associated SS.

Clinical Correlations of Novel Autoantibodies in Patients with Dry Eye

Background

Diagnostic criteria for Sjögren's syndrome (SS) are continually being updated in pursuit of more precise and earlier diagnosis to prevent its complications. Owing to the high rate of false negative traditional serological markers, the need for better serological testing remains.

Objective

To investigate the clinical significance of three recently discovered novel autoantibodies, anti-salivary gland protein 1 (SP1), anti-carbonic anhydrase 6 (CA6), and anti-parotid secretory protein (PSP), in a cohort of dry eye patients with suspected underlying inflammatory/autoimmune disease.

Methods

Medical records of 136 patients with a primary diagnosis of dry eye who underwent laboratory testing between April 2014 and July 2017 were reviewed retrospectively. Data regarding demographic information, ocular and systemic symptoms, previous medical diagnoses, serological test results, and minor salivary gland biopsy results were collected. Dry eye evaluations included tear osmolarity, Schirmer test without anesthesia, conjunctival lissamine green staining, and corneal fluorescein staining in the order listed here.

Results

Of the 136 patients, 9 (9/136, 6.6%) presented with a history of SS, and 9 additional patients (9/127, 7%) received a new diagnosis of SS as a result of evaluations. Fifty-six patients (56/136, 41%) tested positive for at least one of the novel autoantibodies. Fifty-four percent (6/11) of patients with primary SS who underwent the novel serological testing had a positive anti-PSP. Of those, 2 (2/11, 18%) had negative traditional serology and had to undergo minor salivary gland biopsy for definitive diagnosis. Anti-CA6 was associated with increased corneal and conjunctival staining after adjusting for age, sex, and other serologic markers (HR = 1.5, 95% CI = 1.20-1.97, and p = 0.009 and HR = 1.4, 95% CI = 1.04-1.76, and p = 0.02, respectively).

Conclusions

This cross-sectional study demonstrated that anti-CA6 is seen in patients with severe aqueous-deficient dry eye. Whether these patients have an early stage of SS or a different type of autoimmune condition may be determined through longitudinal studies.

Novel autoantibodies in Sjögren's syndrome: A comprehensive review

Sjögren's syndrome is a systemic autoimmune disease characterized by immune- mediated injury of exocrine glands, as well as a diverse array of extraglandular manifestations. B cell over-activation is a key feature of the disease, attested by the wide spectrum of autoantibodies detected in these patients. Up to date, anti- Ro/SSA and anti-La/SSB antibodies are traditional biomarkers for disease classification and diagnosis. On the other hand, the detection of novel autoantibodies in SS has increased in the last years, opening a window of opportunity to denote particular stages of the disease, to establish clinical phenotypes, and to predict long-term complications such as lymphoma. For instance, anti-SP-1, anti-CA6 and anti-PSP antibodies occur in an earlier stage than anti-Ro/La antibodies, and may identify a subset of primary Sjögren's syndrome patients with mild or incomplete disease, whereas anti-cofilin-1, anti- alpha-enolase and anti-RGI2 antibodies are potential biomarkers of MALT lymphoma. Antibody detection is also important to elucidate new aspects of SS pathophysiology, and in the future to permit a phenotype-specific patient approach. Herein we review the literature regarding new autoantibodies in SS and attempt to dissect their usefulness as diagnostic tools, pathogenic role, identification of clinical phenotypes and as predictors of an overlap syndrome.

Prevalence of Novel Candidate Sjogren Syndrome Autoantibodies in the Dry Eye Assessment and Management (DREAM) Study

PURPOSE

To evaluate the prevalence of novel candidate Sjogren syndrome (SS) autoantibodies [salivary protein-1 (SP-1), parotid secretory protein, carbonic anhydrase 6] in the DRy Eye Assessment and Management (DREAM) cohort, a study evaluating the effectiveness of omega-3 fatty acid supplements for the treatment of dry eye.

METHODS

Participants underwent ocular surface examinations and serological testing for traditional and novel SS autoantibodies. Dry eye assessment and management participants were categorized into the following 3 groups: 1) no history of SS or other autoimmune diseases and negative traditional SS autoantibodies (n = 352); 2) no history of SS but a history of other autoimmune diseases (n = 66); and 3) those who met the 2012 American College of Rheumatology SS classification criteria (n = 52).

RESULTS

Eleven percent had a history of SS, and 6% of those without a history of SS most likely had undiagnosed SS. The SS group had a higher prevalence of SP-1 autoantibodies than the group without SS or other autoimmune diseases (33% vs. 19%; P = 0.02) but had no difference in carbonic anhydrase 6 (P = 0.31) or parotid secretory protein autoantibodies (P = 0.33). Participants who were positive for the traditional autoantibodies alone or positive for both traditional and novel autoantibodies had the highest scores for corneal (P = 0.002) and conjunctival staining (P < 0.001).

CONCLUSIONS

Data from this multicenter, prospective study demonstrated that one of the novel candidate autoantibodies, SP-1, is associated with underlying SS and that novel autoantibodies may be associated with worse ocular surface disease. Future longitudinal studies are needed to evaluate their utility in screening patients with dry eye for SS.

Identification of a novel autoantibody against self-vimentin specific in secondary Sjögren's syndrome

Background

Sjögren’s syndrome (SS) is a primary autoimmune disease (pSS) or secondarily associated with other autoimmune diseases (sSS). The mechanisms underlying immune dysregulation in this syndrome remain unknown, and clinically it is difficult to diagnose owing to a lack of specific biomarkers.

Methods

We extracted immunoglobulins (Igs) from the sera of patients with sSS associated with rheumatoid arthritis (RA) and used them to screen a phage display library of peptides with random sequences.

Results

Our results show that an sSS-specific peptide, designated 3S-P, was recognized by sera of 68.2% (60 of 88) patients with sSS, 66.2% of patients with RA-sSS, and 76.5% of patients with systemic lupus erythematosus (SLE)-sSS. The anti-3S-P antibody was scarcely found in patients with pSS (1.8%), RA (1.3%), SLE (4.2%), ankylosing spondylitis (0%), and gout (3.3%), as well as in healthy donors (2%). The 3S-P-binding Igs (antibodies) were used to identify antigens from salivary glands and synovial tissues from patients with sSS. A putative target autoantigen expressed in the synovium and salivary gland recognized by anti-3S-P antibody was identified as self-vimentin.

Conclusions

This novel autoantibody is highly specific in the diagnosis of sSS, and the underlying molecular mechanism of the disease might be epitope spreading involved with vimentin.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1508-5) contains supplementary material, which is available to authorized users.

Investigation of autoantibodies to SP-1 in Chinese patients with primary Sjögren's syndrome

In order to evaluate autoantibody to SP-1 as an early biomarker in pSS, we investigated autoantibody to SP-1 in Chinese patients with primary Sjögren's syndrome (pSS). Autoantibodies to SP-1 are significantly increased in pSS patients compared to RA patients, SLE patients, and healthy people without secondary SS. The presence of anti SP-1 antibodies was negatively correlated with the focus score (FS), RF, and salivary gland function. It was positively correlated with FS=0, RF≤20, and normal salivary gland function. In further studies, the autoantigen SP-1 was identified in ductal epithelia of salivary glands in il14α TG mice by IIF. SP-1 mRNAs expression increased with growing age in il14α TG mice. SP-1 mRNA was also identified in labial biopsies of patients with pSS. In conclusion, autoantibody to SP-1 is an early marker in pSS. It is useful to diagnose pSS patients who lack RF or antibodies to Ro/La.

Autoantibody to MDM2: A potential serological marker of primary Sjogren's syndrome

Introduction

Primary Sjogrens Syndrome (pSS) is one of the autoimmune diseases characterized by polyclonal autoantibody production. The human homologue of the mouse double minute 2 (MDM2) is an important negative regulator of p53. Our previous study indicated that autoantibody to MDM2 can be detected in systemic lupus erythematosus patients. The purpose of this study is to study anti-MDM2 autoantibody in pSS patients.

Methods

Anti-MDM2 autoantibody in sera from 100 pSS patients and 74 normal controls was investigated by ELISA. Positive samples were further confirmed by western blotting. Expression of MDM2 in labial gland tissue from pSS patients and normal controls was checked by immunohistochemistry. The difference in clinical characteristics and laboratory findings between anti-MDM2 positive and anti-MDM2 negative pSS patients was analyzed.

Results

The presence of anti-MDM2 autoantibody in pSS patients was 21.0%, significantly higher than normal controls (5.40%). MDM2 was overexpressed in labial gland from pSS patients. pSS patients with positive anti-MDM2 were characterized by longer disease duration and more lymphocytes focal gathering in labial gland. Prevalence of anemia, thrombocytopenia and anti-SSB was significantly higher in pSS patients with anti-MDM2 autoantibody. Titer of anit-MDM2 was negatively associated with hemoglobin level, platelet count, complement 3 level and complement 4 level, positively associated with European Sjogrens syndrome disease activity index (ESSDAI) and level of IgG.

Conclusions

Anti-MDM2 autoantibody may be used as a potential serological biomarker in pSS disease activity evaluation. Study on the role of anti-MDM2 or MDM2 in pSS may help us know the pathogenesis mechanism of pSS better.

Systemic manifestations of primary Sjögren's syndrome in the NOD.B10Sn-H2b/J mouse model

Animal models that recapitulate human disease are crucial for the study of Sjögren's Syndrome (SS). While several SS mouse models exist, there are few primary SS (pSS) models that mimic systemic disease manifestations seen in humans. Similar to pSS patients, NOD.B10Sn-H2^b/J (NOD.B10) mice develop exocrine gland disease and anti-nuclear autoantibodies. However, the disease kinetics and spectrum of extra-glandular disease remain poorly characterized in this model. Our objective was to characterize local and systemic SS manifestations in depth in NOD.B10 female mice at early and late disease time points. To this end, sera, exocrine tissue, lung, and kidney were analyzed. NOD.B10 mice have robust lymphocytic infiltration of salivary and lacrimal tissue. In addition, they exhibit significant renal and pulmonary inflammation. We identified numerous autoantibodies, including those directed against salivary proteins. In conclusion, the NOD.B10 model recapitulates both local and systemic pSS disease and represents an excellent model for translational studies.

Autoantibodies, detection methods and panels for diagnosis of Sjögren's syndrome

The presence of autoantibodies is one of several hallmarks of Sjögren's Syndrome, the detection of serum autoantibodies has a central role in the diagnosis and classification of Sjögren's syndrome. In this review, we will discuss autoantibodies that are helpful in the diagnosis of Sjögren's syndrome. This includes the traditional autoantibodies for disease classification (ANA, Anti-Ro/SSA, Anti-La/SSB, RF), autoantibodies identified from mouse models (Anti-SP1, Anti- PSP, Anti-CA6, and anti-alpha fodrin) and autoantibodies associated with other autoimmune disease (ACA, AMA, and Anti-CCP). We will also review the methods for the detection of autoantibodies and associated challenges for clinical results reporting. The significance of using an autoantibody panel for the diagnosis of SS will be also be reviewed.

The Potential Role for Early Biomarker Testing as Part of a Modern, Multidisciplinary Approach to Sjögren's Syndrome Diagnosis

Sjögren's syndrome (SS) is a chronic and progressive multisystem autoimmune disease typically managed by rheumatologists. Diagnostic delays are common, due in large part to the non-specific and variable nature of SS symptoms and the slow progression of disease. The hallmark characteristics of SS are dry eye and dry mouth, but there are a broad range of other possible symptoms such as joint and muscle pain, skin rashes, chronic dry cough, vaginal dryness, extremity numbness or tingling, and disabling fatigue. Given that dry eye and dry mouth are typically the earliest presenting complaints, eye care clinicians and dental professionals are often the first point of medical contact and can provide critical collaboration with rheumatologists to facilitate both timely diagnosis and ongoing care of patients with SS. Current diagnostic criteria advocated by the American College of Rheumatology are predicated on the presence of signs/symptoms suggestive of SS along with at least two objective factors such as traditional biomarker positivity, salivary gland biopsy findings, and/or presence of keratoconjunctivitis sicca. Traditional biomarkers for SS include the autoantibodies anti-Sjögren's syndrome-related antigen A (SS-A/Ro), anti-Sjögren's syndrome-related antigen B (SS-B/La), antinuclear antibody (ANA) titers, and rheumatoid factor (RF). While diagnostically useful, these biomarkers have low specificity for SS and are not always positive, especially in early cases of SS. Several newly-identified biomarkers for SS include autoantibodies to proteins specific to the salivary and lacrimal glands [SP-1 (salivary gland protein-1), PSP (parotid secretory protein), CA-6 (carbonic anhydrase VI)]. Data suggest that these novel biomarkers may appear earlier in the course of disease and are often identified in cases that test negative to traditional biomarkers. The Sjö^® test is a commercially available diagnostic panel that incorporates testing for traditional SS biomarkers (anti-SS-A/Ro, anti-SS-B/La, ANA, and RF), as well as three novel, proprietary early biomarkers (antibodies to SP-1, PSP, and CA-6) which provide greater sensitivity and specificity than traditional biomarker testing alone. Timely diagnosis of SS requires appropriate clinical vigilance for potential SS symptoms, referral and collaborative communication among rheumatology, ophthalmology, and oral care professions, and proactive differential work-up that includes both physical and laboratory evaluations.

Evaluation of Autoantibodies in Patients with Primary and Secondary Sjogren's Syndrome

Background:

Antibodies to salivary gland protein 1 (SP1), carbonic anhydrase 6 (CA6) and parotid secretory protein (PSP) were discovered in an animal model of Sjogren’s syndrome (SS). Their expression was noted in patients with SS, especially those with lower focus scores on lip biopsies and those with early disease lacking antibodies to Ro and La.

Objective:

The current studies evaluated these autoantibodies in patients with long-standing SS expressing high levels of anti-Ro antibodies and in patients with Sjogren’s syndrome secondary to systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and mixed connective tissue disease (MCTD).

Method:

Sera were obtained from patients and evaluated by ELISA for IgG, IgA and IgM antibodies to SP1, CA6 and PSP.

Results:

IgA anti-CA6 antibodies were noted in 38% of these patients, but anti-SP1, CA6 and PSP IgM or IgG antibodies were identified only in a minority of patients. In patients with secondary SS, antibodies to SP1/CA6/PSP were more sensitive and specific than anti-Ro .

Conclusion:

While more studies are needed, antibodies to SP1, CA6 and PSP provide valuable markers for the diagnosis of primary and secondary SS, especially early in the course of the disease.

Dysfunctional tear syndrome: dry eye disease and associated tear film disorders - new strategies for diagnosis and treatment

Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition.

Characterization of the serological biomarkers associated with Sjögren's syndrome in patients with recalcitrant dry eye disease

Purpose

The purpose was to characterize the biomarkers associated with Sjögren’s syndrome (SS) identified in the serological samples of patients with recalcitrant dry eye disease; additionally, the modalities utilized in the treatment of dry eye disease were evaluated for subsets of patients with and without SS.

Patients and methods

Data for this retrospective, single-center, pilot study were based on a chart review of 48 sequential patients with recalcitrant dry eye who were evaluated for SS via serological analysis. Data presented include the presence of the autoantibodies identified through the serological biomarker analysis and identification of the concurrent dry eye treatment modalities.

Results

Eleven out of 48 patients (23%) tested positive for biomarkers associated with SS. Autoantibodies for salivary protein-1, parotid secretory protein 1, and carbonic anhydrase VI, markers associated with the early development of SS, were detected in 91% (ten out of eleven) of the patients who tested positive for SS, whereas 27% (three out of eleven) of patients tested positive for the traditional SS markers, SS-A and/or SS-B. Common treatment modalities utilized in SS patients included omega-3 supplements (82%), topical cyclosporine (74%), and artificial tear solutions (64%), as compared to omega-3 supplements (80%), hot-mask therapy (77%), and artificial tear solutions (77%), in SS-negative patients.

Conclusion

Evaluation for salivary protein-1, parotid secretory protein 1, and carbonic anhydrase VI biomarkers allows for identification of a subset of patients with biomarkers associated with SS that may not be identified through the traditional assessments (SS-A/SS-B). Earlier recognition of SS biomarkers allows for a confirmatory diagnosis and appropriate management of this systemic, progressive condition.

Gastrointestinal disease in Sjogren's syndrome: related to food hypersensitivities

Patients with Sjogren’s syndrome (SS) frequently have irritable bowel like symptoms (IBS). Some have celiac sprue. The current studies were designed to examine the presence of food hypersensitivities in a population of patients with SS and IBS. Ten patients were selected from the autoimmune disease clinics at SUNY at Buffalo who had SS and IBS symptoms. Food hypersensitivities were determined by specific IgG ImmunoCAP^® assays. Symptoms of abdominal pain, bloating, diarrhea and joint pain were eliminated with dietary restriction of foods to which hypersensitivity was demonstrated. Symptoms recurred with re-institution of offending foods. Resolution of fatigue required elimination of offending foods as well as treatment of underlying metabolic disorders. The presence of IBS in patients with SS should lead to investigation of food hypersensitivities as possible culprits.

Plant-Derived Chimeric Virus Particles for the Diagnosis of Primary Sjögren Syndrome

Plants are ideal for the production of protein-based nanomaterials because they synthesize and assemble complex multimeric proteins that cannot be expressed efficiently using other platforms. Plant viruses can be thought of as self-replicating proteinaceous nanomaterials generally stable and easily produced in high titers. We used Potato virus X (PVX), chimeric virus particles, and Cowpea mosaic virus, empty virus-like particles to display a linear peptide (lipo) derived from human lipocalin, which is immunodominant in Sjögren's syndrome (SjS) and is thus recognized by autoantibodies in SjS patient serum. These virus-derived nanoparticles were thus used to develop a diagnostic assay for SjS based on a direct enzyme linked immunosorbent assay format. We found that PVX-lipo formulations were more sensitive than the chemically synthesized immunodominant peptide and equally specific when used to distinguish between healthy individuals and SjS patients. Our novel assay therefore allows the diagnosis of SjS using a simple, low-invasive serum test, contrasting with the invasive labial biopsy required for current tests. Our results demonstrate that nanomaterials based on plant viruses can be used as diagnostic reagents for SjS, and could also be developed for the diagnosis of other diseases.

Investigation of novel autoantibodies in Sjogren's syndrome utilizing Sera from the Sjogren's international collaborative clinical alliance cohort

Background

Sjogren’s syndrome (SS) is a chronic autoimmune disease mainly affecting salivary and lacrimal glands. Current diagnostic criteria for SS utilize anti-Ro and anti-La as serological markers. Animal models for SS have identified novel autoantibodies, anti-salivary gland protein 1 (SP1), anti-carbonic anhydrase 6 (CA6) and parotid secretory protein (PSP). These novel antibodies are seen in the animals at an earlier stage of SS than anti-Ro and anti-La. The current studies were designed to evaluate these novel autoantibodies in the sera of well-characterized patients with dry eyes and dry mouth and lip biopsies from the Sjogren’s International Collaborative Clinical Alliance (SICCA) to determine if they indeed identify SS with less severe disease than patients expressing anti-Ro and anti-La.

Methods

Sera were obtained from SICCA registry in patients for whom lymphocytic foci per 4 mm² on the lip biopsies was either 0 (F = 0), <1 (F <1) or > 3 (F >3). ELISA assays were utilized to evaluate these sera for anti-Ro, anti-La, anti-SP1, anti-CA6, and anti-PSP.

Results

In patients with dry eyes and dry mouth but F = 0, increased expression of anti- CA6 was noted compared to the F <1 group (p = .032) or the F > 3 group (p = .006). Neither anti-PSP nor anti-SP1 reached statistical significance because of the small numbers in the F0 group, although there was a trend for their expression to be higher in the F0 group. On the other hand, the expression of anti-Ro was significantly reduced in the F0 group compared to the F <1 (p = .0021) and F > 3 (p = .0003) groups. The reduced expression of anti-La in the F0 group compared to the F <1 and F > 3 groups did not quite reach statistical significance.

Conclusions

Anti-Ro and anti-La identify patients with SS and more severe disease than anti-SP1, anti-CA6, and anti-PSP. More studies are needed to identify the timing in the course of SS when these different autoantibodies are expressed and/or whether they are expressed in patients with different clinical manifestations.