Autoantibodies in Sjögren's Syndrome

Sialylation status in placentas from anti-Ro/SSA- and anti-La/SSB-positive pregnant women

Women affected by different autoimmune diseases and displaying positivity for anti-Ro/SSA and anti-La/SSB autoantibodies are at high risk of adverse pregnancies in which placental dysfunction seems to play a determinant role. Sialylation is known to have important implications in the maintenance of the normal morpho-functional features of the placenta. Hence, the present study aimed to investigate possible changes in the distribution and content of sialic acids (Sias) with different glycosidic linkages (i.e., α2,3 and α2,6 Galactose- or N-acetyl-Galactosamine-linked Sias, and polysialic acid) in placentas from anti-Ro/SSA- and anti-La/SSB-positive pregnant women with autoimmune diseases by using lectin histochemistry and polysialic acid immunohistochemistry. Our findings revealed lower levels of α2,3-linked Sias in the trophoblast and basement membrane and/or basal plasma membrane of the pathological cases respect to control placentas. Some vessels of the pathological cases displayed α2,3-linked Sias. α2,6-linked Sias positivity was detected in the trophoblast and in some vessels of the pathological cases, while in control samples it was present only in the vessels. Lower levels of polysialic acid were observed in the trophoblast of pathological cases compared to controls. Collectively, our findings suggest that multiple changes in the sialylation status of placenta might affect placental morpho-functional features in anti-Ro/SSA- and anti-La/SSB-positive pregnancies.

Endometriosis and Sjögren's syndrome: Bidirectional associations in population-based 15-year retrospective cohorts

INTRODUCTION

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disorder affecting salivary and lacrimal glands, while endometriosis involves uterine-like tissue growth outside the uterus, causing pelvic pain and infertility. Investigating their intricate relationship using real-world data is crucial due to limited research on their connection.

MATERIAL AND METHODS

This population-based cohort study included patients with endometriosis and controls without endometriosis. Propensity score matching was used to balance baseline differences in demographic and clinic characteristics between the two groups. Cox proportional hazards model were used to estimate the effect of endometriosis on the risk of new-onset pSS over time. A symmetrical cohort study, including patients with pSS and propensity score-matched controls without pSS, was conducted to investigate the effect of pSS on the risk of endometriosis over time. To elaborate on the mechanisms linking endometriosis and pSS, Ingenuity Pathway Analysis was performed to identify activated pathways in eutopic endometrium from patients with endometriosis and parotid tissues from patients with pSS.

RESULTS

A total of 15 947 patients with endometriosis and 15 947 propensity score-matched controls without endometriosis were included. Patients with endometriosis presented a significantly greater risk of pSS compared to non-endometriosis controls (adjusted hazard ratio, aHR = 1.57, 95% CI = 1.29-1.91, p < 0.001). In the symmetrical cohort study, which included 4906 pSS patients and 4,906 propensity score-matched controls without pSS, patients with pSS were found to be at a significantly higher risk of endometriosis compared to non-pSS controls (aHR = 1.51, 95% CI = 1.12-2.04, p = 0.012). Ingenuity Pathway Analysis showed that the underlying cellular mechanisms involved autoimmune-related pathways, including activation of dendritic cell maturation, and chronic inflammatory pathways, including the fibrosis signaling pathway.

CONCLUSIONS

These findings support a bidirectional association between endometriosis and pSS, which may be driven by dendritic cell maturation and fibrosis signaling pathways.

Ro60-Roles in RNA Processing, Inflammation, and Rheumatic Autoimmune Diseases

The Ro60/SSA2 autoantigen is an RNA-binding protein and a core component of nucleocytoplasmic ribonucleoprotein (RNP) complexes. Ro60 is essential in RNA metabolism, cell stress response pathways, and cellular homeostasis. It stabilises and mediates the quality control and cellular distribution of small RNAs, including YRNAs (for the 'y' in 'cytoplasmic'), retroelement transcripts, and misfolded RNAs. Ro60 transcriptional dysregulation or loss of function can result in the generation and release of RNA fragments from YRNAs and other small RNAs. Small RNA fragments can instigate an inflammatory cascade through endosomal toll-like receptors (TLRs) and cytoplasmic RNA sensors, which typically sense pathogen-associated molecular patterns, and mount the first line of defence against invading pathogens. However, the recognition of host-originating RNA moieties from Ro60 RNP complexes can activate inflammatory response pathways and compromise self-tolerance. Autoreactive B cells may produce antibodies targeting extracellular Ro60 RNP complexes. Ro60 autoantibodies serve as diagnostic markers for various autoimmune diseases, including Sjögren's disease (SjD) and systemic lupus erythematosus (SLE), and they may also act as predictive markers for anti-drug antibody responses among rheumatic patients. Understanding Ro60's structure, function, and role in self-tolerance can enhance our understanding of the underlying molecular mechanisms of autoimmune conditions.

Profiles of peripheral B cell subsets in a cohort of primary Sjögren's syndrome patients and their potential clinical significance

Background/purpose

Primary Sjögren's syndrome is a prototypical autoimmune disease, with B cell dysfunction as a dominant feature. Further insights into distribution of B cell subsets in primary Sjögren's syndrome are urgently required to identify the most appropriate target subpopulation. We aimed to evaluate the profiles of B lymphocyte subpopulations in primary Sjögren's syndrome patients and to investigate their clinical significance.

Materials and methods

Thirty primary Sjögren's syndrome patients and 15 age-and sex-matched healthy controls were recruited. Peripheral B cell subsets were analyzed by flow cytometry.

Results

Compared to healthy controls, circulating CD19+ B cells, CD19+CD20- B cells, CD19+CD27-IgD+ naïve B cells, CD19+IgD+CD38high plasmablasts, CD19+CD24highCD38high transitional B cells and CD19+CD20-CD27+CD38+ plasma cells were elevated in patients with primary Sjögren's syndrome, whereas CD19+CD27+ memory B cells, CD19+CD27-IgD- double negative B cells and CD19+CD24hiCD27+ Bregs were decreased. Furthermore, the percentage of circulating CD19+CD20-CD27+CD38+ plasma cells was positively correlated with serum IgG levels and the proportional area of lymphocytic infiltration of labial gland.

Conclusion

We identified a comprehensive B lymphocyte subset distribution profile in primary Sjögren's syndrome. Moreover, we detected a clinical significance of CD19+CD20-CD27+CD38+ plasma cells, suggesting that these cells might play a key role in disease pathology and represent potential therapeutic targets.

Sicca syndrome/Sjögren's disease associated with cancer immunotherapy: a narrative review on clinical presentation, biomarkers, and management

INTRODUCTION

Almost one-quarter of immune checkpoint inhibitor (ICI) recipients experience sicca syndrome, while Sjögren's disease (SjD) is estimated at 0.3-2.5%, possibly underreported.

AREAS COVERED

This narrative review (Medline/Embase until January/31/2024) addresses the pathophysiology, incidence, demographic/clinical features, biomarkers, labial salivary gland biopsy (LSGB), fulfillment of the idiopathic SjD (iSjD) classificatory criteria, differential diagnosis, and management of sicca syndrome/SjD associated with ICIs.

EXPERT OPINION

SjD associated with ICIs is underdiagnosed, since studies that performed the mandatory SjD investigation identified that 40-60% of patients with sicca syndrome associated with ICIs meet the iSjD classificatory criteria. LSGB played a fundamental role in recognizing these cases, as most of them had negative anti-Ro/SS-A antibody. Despite the finding of focal lymphocytic sialoadenitis in LSGB samples mimicking iSjD, immunohistochemical analysis provided novel evidence of a distinct pattern for sicca syndrome/SjD associated with ICIs compared to iSjD. The former has scarcity of B lymphocytes, which are a hallmark of iSjD. Additionally, patients with sicca syndrome/SjD associated with ICIs have demographical/clinical/serological and treatment response dissimilarities compared to iSjD. Dryness symptoms are more acute in the former than in iSjD, with predominance of xerostomia over xerophthalmia, and partial/complete response to glucocorticoids. Dryness symptoms in ICI-treated patients warrant prompt SjD investigation.

Mitochondrial Dysfunction and Fatigue in Sjögren's Disease

Objectives

Sjögren's disease (SjD) is a common exocrine disorder typified by chronic inflammation and dryness, but also profound fatigue, suggesting a pathological basis in cellular bioenergetics. In healthy states, damaged or dysfunctional mitochondrial components are broken down and recycled by mitophagy, a specialized form of autophagy. In many autoimmune disorders, however, evidence suggests that dysfunctional mitophagy allows poorly functioning mitochondria to persist and contribute to a cellular milieu with elevated reactive oxygen species. We hypothesized that mitophagic processes are dysregulated in SjD and that dysfunctional mitochondria contribute to overall fatigue. We sought to link fatigue with mitochondrial dysfunction directly in SjD, heretofore unexamined, and further sought to assess the pathogenic extent and implications of dysregulated mitophagy in SjD.

Methods

We isolated pan T cells via negative selection from the peripheral blood mononuclear cells of 17 SjD and 8 age-matched healthy subjects, all of whom completed fatigue questionnaires prior to phlebotomy. Isolated T cells were analyzed for mitochondrial oxygen consumption rate (OCR) and glycolysis using Seahorse, and linear correlations with fatigue measures were assessed. A mitophagy transcriptional signature in SjD was identified by reanalysis of whole-blood microarray data from 190 SjD and 32 healthy subjects. Differential expression analyses were performed by case/control and subgroup analyses comparing SjD patients by mitophagy transcriptional cluster against healthy subjects followed by bioinformatic interpretation using gene set enrichment analysis.

Results

Basal OCR, ATP-linked respiration, maximal respiration, and reserve capacity were significantly lower in SjD compared to healthy subjects with no observed differences in non-mitochondrial respiration, basal glycolysis, or glycolytic stress. SjD lymphocytic mitochondria show structural alterations compared to healthy subjects. Fatigue scores related to pain/discomfort in SjD correlated with the altered OCR. Results from subgroup analyses by mitophagic SjD clusters revealed highly variable inter-cluster differentially expressed genes (DEGs) and expanded the number of SjD-associated gene targets by tenfold within the same dataset.

Conclusion

Mitochondrial dysfunction, associated with fatigue, is a significant problem in SjD and warrants further investigation.

Seronegative patients with primary Sjögren's syndrome and non-pSS sicca test positive for anti-SSA/Ro52 and -Ro60 in saliva

OBJECTIVES

Testing for anti-SSA/Ro antibodies in serum is essential in the diagnostic work-up for primary Sjögren's syndrome (pSS). In this study, we aimed to validate our previous assay for detection of salivary anti-SSA/Ro52, and to develop assays for detection of salivary anti-SSA/Ro60 and for detection of anti-Ro52 and -Ro60 in plasma using the electric field-induced release and measurement (EFIRM) platform.

METHODS

Whole saliva samples from two independent Danish cohorts (DN1 and DN2) including 49 patients with pSS, 73 patients with sicca symptoms, but not fulfilling the classification criteria for pSS (non-pSS sicca), and 51 healthy controls (HC), as well as plasma samples from the DN1 cohort were analyzed using EFIRM to detect anti-SSA/Ro52 and -Ro60.

RESULTS

In the DN1 cohort, 100 % in the pSS group and 16 % in the non-pSS sicca group were serum anti-SSA/Ro positive by ELISA. EFIRM detected anti-SSA (Ro52 and/or -Ro60) in plasma and saliva in 100 % and 96 % patients with pSS, and 16 % and 29 % with non-pSS sicca. In the DN2 cohort, 80 % patients with pSS and 26 % with non-pSS sicca were serum anti-SSA/Ro positive. Salivary anti-SSA discriminated patients with pSS from HC and non-pSS sicca with an AUC range of 0.74-0.96 in the DN1 and DN2 cohorts. EFIRM discriminated pSS from non-pSS sicca with an AUC of 0.98 in plasma.

CONCLUSION

Our findings suggest that salivary anti-SSA/Ro antibodies are potential discriminatory biomarkers for pSS, which may also identify seronegative patients, addressing the unmet clinical need of early detection and stratification of pSS.

The titers of antinuclear antibodies are associated with the degree of inflammation and organ damage in Primary Sjögren's Syndrome

Primary Sjögren's Syndrome (pSS) falls within the category of connective tissue diseases, characterized by the presence of autoantibodies such as antinuclear antibodies (ANA). However, according to the classification criteria for pSS, some patients may exhibit a negative result for autoantibodies. Patients with a negative result for autoantibodies may lack typical features of connective tissue diseases, and the immunological state as well as the extent of organ involvement and damage may differ from those with positive autoantibodies. This study aims to compare the clinical phenotypes of patients with positive and negative autoantibodies, providing insights for disease classification and treatment selection for clinicians. Patients with pSS were grouped based on the presence and titers of their autoantibodies. Subsequently, differences in organ damage and laboratory indicators were compared between these groups, aiming to analyze the value of autoantibody titers in assessing the condition of pSS. (1) Patients with positive ANA exhibited elevated levels of inflammatory indicators, including ESR, IgG levels, lip gland biopsy pathology grade, and overall organ involvement, in comparison with patients with negative ANA (P < 0.05). Furthermore, ANA-positivity correlated with a higher occurrence of multi-organ damage, particularly affecting the skin, mucous membranes, and the hematological system (P < 0.05). (2) As ANA titers increased, patients demonstrated elevated levels of IgG and an escalation in organ involvement (P < 0.05). (3) Patients in the positive autoantibody group (positive for antinuclear antibodies, anti-SSA, or anti-SSB antibodies) had higher IgG levels compared to the negative group (P < 0.05). (4) Patients with positive anti-SSA and anti-SSB antibodies exhibited higher levels of inflammatory indicators and IgG compared to other patients (P < 0.05); however, no significant differences were observed in terms of organ involvement and organ damage. Patients with positive ANA in pSS typically exhibit higher levels of inflammation and an increased likelihood of experiencing multi-organ damage. Furthermore, as the ANA titers increase, both inflammation levels and the risk of multi-organ damage also escalate. Additionally, the presence of anti-SSA and anti-SSB antibodies may contribute to an elevated risk of increased inflammation levels, but does not increase the risk of organ damage.

Exploring Sjögren's syndrome through interdisciplinary perspectives: a concise review

Dr. Henrik Sjögren after whom Sjögren's Syndrome is named, was a Swedish ophthalmologist who identified the syndrome which had three main symptoms namely, dry eyes, dry mouth, and arthritis. His contributions also highlighted the systemic complications of the syndrome which made our understanding of this disease better. Since then, there have been several studies on Sjögren's Syndrome (SS) of which two of them have changed the perception of the disease's prevalence. The first was a British study in the late 1990s which indicated this syndrome was no more a rare condition. The second is a 2008 study in the US which placed the syndrome as the second most prevalent autoimmune disease after rheumatoid arthritis (RA). Being one of the most prevalent autoimmune disease, there is a pressing need for a more profound and comprehensive understanding of the syndrome. This review endeavors to offer a comprehensive overview of the disease, encompassing its prevalence, manifestations, mechanisms, genetic factors, diagnostic methods, and treatment options. This review additionally offers the āyurvedic viewpoint on SS and its symptoms. This supplementary insight has the potential to contribute to the development of an integrated and holistic approach to managing the condition.

Exploring Salivary Epithelial Dysfunction in Sjögren's Disease

Sjögren's Disease (SjD) is an autoimmune disease of the exocrine tissues. Etiological events result in the loss of epithelial homeostasis alongside extracellular matrix (ECM) destruction within the salivary and lacrimal glands, followed by immune cell infiltration. In this review, we have assessed the current understanding of epithelial-mesenchymal transition (EMT)-associated changes within the salivary epithelium potentially involved in salivary dysfunction and SjD pathogenesis. We performed a PubMed literature review pertaining to the determination of pathogenic events that lead to EMT-related epithelial dysfunction and signaling in SjD. Molecular patterns of epithelial dysfunction in SjD salivary glands share commonalities with EMT mediating wound healing. Pathological changes altering salivary gland integrity and function may precede direct immune involvement while perpetuating MMP9-mediated ECM destruction, inflammatory mediator expression, and eventual immune cell infiltration. Dysregulation of EMT-associated factors is present in the salivary epithelium of SjD and may be significant in initiating and perpetuating the disease. In this review, we further highlight the gap regarding mechanisms that drive epithelial dysfunction in salivary glands in the early or subclinical pre-lymphocytic infiltration stages of SjD.

British Society for Rheumatology guideline on management of adult and juvenile onset Sjögren disease

Sjögren disease (SD) is a chronic, autoimmune disease of unknown aetiology with significant impact on quality of life. Although dryness (sicca) of the eyes and mouth are the classically described features, dryness of other mucosal surfaces and systemic manifestations are common. The key management aim should be to empower the individual to manage their condition-conserving, replacing and stimulating secretions; and preventing damage and suppressing systemic disease activity. This guideline builds on and widens the recommendations developed for the first guideline published in 2017. We have included advice on the management of children and adolescents where appropriate to provide a comprehensive guideline for UK-based rheumatology teams.

Development of a nomogram for membranous nephropathy prediction in patients with primary Sjögren's syndrome: a 6-year retrospective study

Objectives

Nephritis is a life-threatening complication of primary Sjögren's syndrome (pSS), with membranous nephropathy (MN) being prevalent. Renal biopsy is the gold standard for MN diagnosis, but it is invasive and cannot be repeatedly performed. This study aimed to develop a nomogram for the prediction of MN in patients with pSS.

Methods

This retrospective study included patients with pSS admitted to the Rheumatology and Immunology Department of the First Affiliated Hospital of China Medical University between January 2015 and January 2021. A nomogram was developed using multivariable logistic regression analysis and evaluated using receiver operating characteristic (ROC) curve analysis. Bootstrap resampling analysis (1,000 times) was performed to evaluate the nomogram for discrimination and the calibration curve for consistency.

Results

A total of 237 patients with pSS [aged 53.00 (44.00, 61.00) years] were included, with 35 pSS-MN patients. Based on clinical practice and multivariable logistic regression analysis, seven variables associated with pSS-MN were selected, including white blood cells, creatine, complement 3, rheumatoid factor, antinuclear antibodies, anti-SSA antibody, and interstitial lung disease. The area under the ROC curve was 0.860 (95% confidence interval: 0.796-0.919), indicating good predictive power. In addition, the nomogram exhibited excellent performance, as demonstrated by the calibration curve and decision curve analysis.

Conclusion

This study developed a risk prediction nomogram for MN in patients with pSS, with high predictive power. It may be used to improve the management of patients with pSS.

Molecular mechanisms of saliva secretion and hyposecretion

The exocrine salivary gland secretes saliva, a fundamental body component to maintain oral homeostasis. Saliva is composed of water, ions, and proteins such as amylase, mucins, and immunoglobulins that play essential roles in the digestion of food, lubrication, and prevention of dental caries and periodontitis. An increasing number of people experience saliva hyposecretion due to aging, medications, Sjögren's syndrome, and radiation therapy for head and neck cancer. However, current treatments are mostly limited to temporary symptomatic relief. This review explores the molecular mechanisms underlying saliva secretion and hyposecretion to provide insight into putative therapeutic targets for treatment. Proteins implicated in saliva secretion pathways, including Ca2+ -signaling proteins, aquaporins, soluble N-ethylmaleimide-sensitive factor attachment protein receptors, and tight junctions, are aberrantly expressed and localized in patients with saliva hyposecretion, such as Sjögren's syndrome. Analysis of studies on the mechanisms of saliva secretion and hyposecretion suggests that crosstalk between fluid and protein secretory pathways via Ca2+ /protein kinase C and cAMP/protein kinase A regulates saliva secretion. Impaired crosstalk between the two secretory pathways may contribute to saliva hyposecretion. Future research into the detailed regulatory mechanisms of saliva secretion and hyposecretion may provide information to define novel targets and generate therapeutic strategies for saliva hyposecretion.

TLR7 activation of age-associated B cells mediates disease in a mouse model of primary Sjögren's disease

Primary Sjögren's disease (pSD) (also referred to as Sjögren's syndrome) is an autoimmune disease that primarily occurs in women. In addition to exocrine gland dysfunction, pSD patients exhibit B cell hyperactivity. B cell-intrinsic TLR7 activation is integral to the pathogenesis of systemic lupus erythematosus, a disease that shares similarities with pSD. The role of TLR7-mediated B cell activation in pSD, however, remains poorly understood. We hypothesized that age-associated B cells (ABCs) were expanded in pSD and that TLR7-stimulated ABCs exhibited pathogenic features characteristic of disease. Our data revealed that ABC expansion and TLR7 expression were enhanced in a pSD mouse model in a Myd88-dependent manner. Splenocytes from pSD mice showed enhanced sensitivity to TLR7 agonism as compared with those derived from control animals. Sort-purified marginal zone B cells and ABCs from pSD mice showed enhanced inflammatory cytokine secretion and were enriched for antinuclear autoantibodies following TLR7 agonism. Finally, IgG from pSD patient sera showed elevated antinuclear autoantibodies, many of which were secreted preferentially by TLR7-stimulated murine marginal zone B cells and ABCs. These data indicate that pSD B cells are hyperresponsive to TLR7 agonism and that TLR7-activated B cells contribute to pSD through cytokine and autoantibody production. Thus, therapeutics that target TLR7 signaling cascades in B cells may have utility in pSD patients.

Are the cut-offs of the rheumatoid factor and anti-cyclic citrullinated peptide antibody different to distinguish rheumatoid arthritis from their primary differential diagnoses?

OBJECTIVE

Rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (anti-CCP) are commonly used for diagnosis of rheumatoid arthritis (RA), although other rheumatic diseases with arthritis can test positive. This study aimed to determine the cutoff values for RF and anti-CCP with the best diagnostic performance in a sample of patients with RA, compared with other rheumatic diseases.

METHODS

This was a descriptive, prospective study. EUROINMMUN enzyme-linked immunosorbent assays for RF isotypes immunoglobulin (Ig) A (IgA), IgG and IgM and third-generation assay IgG for anti-CCP were used in serum samples of patients with RA, other rheumatic diseases and healthy subjects. The cutoff with the best diagnostic performance was determined by the Youden Index and receiver operating characteristic analysis Results: Three hundred and thirty-two serum samples were analysed. The cutoffs proposed in our population were for RF in RA patients versus other rheumatic diseases, and healthy subjects IgM 135 IU/mL, for each disease, compared with RA, were psoriatic arthritis (Psa) IgA 47.2 IU/mL, clinically suspicious arthralgia (CSA) IgA 39.5 IU/mL, primary Sjögren's syndrome (pSS) IgM 180.6 IU/mL, systemic lupus erythematosus (SLE) IgA 42.6 IU/mL, primary fibromyalgia (pFM) IgM 68.6 IU/mL, osteoarthritis (OA) IgM 48 IU/mL, gout IgM 117 IU/mL and healthy IgM 16.3 IU/mL. For anti-CCP, in RA patients versus other rheumatic diseases, and healthy subjects 6.95 IU/mL, for each disease, compared with RA, were Psa 6.8 IU/mL, CSA 9.95 IU/mL, pSS 20.7 IU/mL, SLE 6 IU /mL, pFM 11.8 IU/mL, OA 11.9 IU/mL, gout 5 IU/mL and healthy 5 IU/mL.

CONCLUSION

Irrespective of the manufacturer's suggested cutoff, the RA versus differential diagnosis cutoffs must be considered.

Advances in Sjögren's Syndrome Dry Eye Diagnostics: Biomarkers and Biomolecules beyond Clinical Symptoms

Sjögren's syndrome dry eye (SSDE) is a subset of Sjögren's syndrome marked by dry eye symptoms that is distinct from non-Sjögren's syndrome dry eye (NSSDE). As SSDE can lead to severe complications, its early detection is imperative. However, the differentiation between SSDE and NSSDE remains challenging due to overlapping clinical manifestations. This review endeavors to give a concise overview of the classification, pathophysiology, clinical features and presentation, ocular and systemic complications, clinical diagnosis, and management of SSDE. Despite advancements, limitations in current diagnostic methods underscore the need for novel diagnostic modalities. Thus, the current review examines various diagnostic biomarkers utilized for SSDE identification, encompassing serum, salivary, and tear analyses. Recent advancements in proteomic research and exosomal biomarkers offer promising diagnostic potential. Through a comprehensive literature review spanning from 2016 to 2023, we highlight molecular insights and advanced diagnostic modalities that have the potential to enhance our understanding and diagnosis of SSDE.

Confocal Microscopy Abnormalities Preceding Antibody Positivity and Manifestations of Sjogren's Syndrome

An asymptomatic 26-year-old woman underwent confocal microscopy as part of a control population for a research study. Images revealed reduced sub-basal corneal nerve density and multiple activated dendritic cells. Three years later, she presented with a self-limited cutaneous vasculitis in her lower extremities which prompted an evaluation for autoimmune diseases. Laboratory testing revealed positive antinuclear antibodies (1:320, thick granular pattern), and anti-SSA/SSB (SSA, 53.6 U/mL, moderately positive; SSB, 142.7 U/mL, strongly positive). Two weeks later, she presented with ocular pain and an ophthalmologic examination revealed ocular surface staining. An ocular ultrasound was consistent with posterior scleritis. Based on this picture, a diagnosis of Sjögren syndrome (SS) was made. SS is a chronic autoimmune disease that can present with symptoms that diminish the patient's quality of life. Confocal microscopy might be a valuable tool for the early diagnosis of disease.

Genomic DNA activates the AIM2 inflammasome and STING pathways to induce inflammation in lacrimal gland myoepithelial cells

PURPOSE

Primary Sjögren's syndrome (pSS) is an autoimmune disease that mainly attacks the lacrimal glands causing severe aqueous-deficient dry eye. Clinical evidence indicates the DNA sensing mechanism in the pathogenesis of pSS. The purpose of the present study is to determine the pro-inflammatory effect of self-genomic DNA (gDNA) on myoepithelial cells (MECs), which along with acinar and ductal cells is a major cell type of the lacrimal gland.

METHOD

MECs primary culture was acquired from female C57BL6J mice. Genomic DNA was extracted from the spleen of the same animal. The MECs were challenged with self-gDNA. The cytokine secretion was detected using supernatant by enzyme-linked immunosorbent assay (ELISA). The activation of inflammasomes was determined using FAM-FLICA. Cryosections of NOD.B10.H2b mouse model of pSS were obtained for immunofluorescence microscopy (IF), with Balb/C as control.

RESULT

Treatment with gDNA activated AIM2 inflammasome assembly and function, leading to secretion of interleukin (IL)-1β and IL-18 in MECs. The stimulation of IL-1β secretion by gDNA appeared to be solely at the post-translational level, whereas IL-18 secretion was a combination of increased protein synthesis and post-translational modification. Genomic DNA also induced the activation of STimulators of INterferon Genes (STING), which correlated to the activation of STING in the lacrimal gland from the NOD.B10.H2b mouse. STING activation led to the secretion of IFN-β via Nuclear Factor-κB (NF-κB). The IFN-β further enhances the secretion of IL-1β. The contractility of MECs was disabled by treatment with gDNA or poly AnT, independent of the level of intracellular [Ca2+].

CONCLUSION

Self-gDNA induces a proinflammatory response in lacrimal gland MECs by activating both the AIM2 inflammasome and STING and thus may contribute to the pathogenesis of pSS.

Current Views on Pathophysiology and Potential Therapeutic Targets in Sjögren's Syndrome: A Review from the Perspective of Viral Infections, Toll-like Receptors, and Long-Noncoding RNAs

Sjögren's syndrome (SS) is a rheumatic disease characterized by sicca and extraglandular symptoms, such as interstitial lung disease and renal tubular acidosis. SS potentially affects the prognosis of patients, especially in cases of complicated extraglandular symptoms; however, only symptomatic therapies against xerophthalmia and xerostomia are currently included in the practice guidelines as recommended therapies for SS. Considering that SS is presumed to be a multifactorial entity caused by genetic and environmental factors, a multidisciplinary approach is necessary to clarify the whole picture of its pathogenesis and to develop disease-specific therapies for SS. This review discusses past achievements and future prospects for pursuing the pathophysiology and therapeutic targets for SS, especially from the perspectives of viral infections, toll-like receptors (TLRs), long-noncoding RNAs (lncRNAs), and related signals. Based on the emerging roles of viral infections, TLRs, long-noncoding RNAs and related signals, antiviral therapy, hydroxychloroquine, and vitamin D may lower the risk of or mitigate SS. Janus-kinase (JAK) inhibitors are also potential novel therapeutic options for several rheumatic diseases involving the JAK-signal transducer and activator of transcription pathways, which are yet to be ascertained in a randomized controlled study targeting SS.

Validation of an indirect ELISA assay for assessment of autoantibodies against full-length TRIM21 and its individual domains

Anti-SSA-autoantibodies are common in patients with rheumatologic disease, especially Sjögren's syndrome, systemic lupus erythematosus and rheumatoid arthritis. They consist of both autoantibodies towards Ro60 and Ro52, the latter also known as TRIM21. TRIM21 is an intracellular protein consisting of four domains; PRY/SPRY, Coiled-Coil, B-box and RING. The aim of this study was to establish an indirect ELISA detecting autoantibodies towards both the full-length TRIM21 protein and its four domains. We expressed the five constructs, created, and validated indirect ELISA protocols for each target using plasma from anti-SSA positive patients and healthy controls. Our findings were validated to the clinically used standards. We measured significantly higher levels of autoantibodies towards our full-length TRIM21, and the PRY/SPRY, Coiled-Coil and RING domains in patients compared to healthy controls. No significant difference in the level of autoantibodies were detected against the B-box domain. Our setups had a signal to noise ratio in the range of 30 to 184, and an OD between 2 and 3. Readings did not decline using NaCl of 500 mM as wash, affirming the high binding affinity of the autoantibodies measured. Our protocols allow us to further study the different autoantibodies of anti-SSA positive patients. This creates the possibility to stratify our patients into subgroups regarding autoantibody profile and specific pheno- or endotype.

Identification of Salivary Metabolic Signatures Associated with Primary Sjögren's Disease

Sjögren's disease (SjD) is the second most prevalent autoimmune disorder that involves chronic inflammation of exocrine glands. Correct diagnosis of primary SjD (pSjD) can span over many years since disease symptoms manifest only in advanced stages of salivary and lachrymal glandular destruction, and consensus diagnostic methods have critical sensitivity and selectivity limitations. Using nuclear magnetic resonance (NMR) spectroscopy, we determined the composition of metabolites in unstimulated saliva samples from 30 pSjD subjects and 30 participants who do not have Sjögren's disease (non-Sjögren's control group, NS-C). Thirty-four metabolites were quantified in each sample, and analysis was conducted on both non-normalized (concentration) and normalized metabolomics data from all study participants (ages 23-78) and on an age-restricted subset of the data (ages 30-70) while applying false discovery rate correction in determining data significance. The normalized data of saliva samples from all study participants, and of the age-restricted subset, indicated significant increases in the levels of glucose, glycerol, taurine, and lactate, as well as significant decreases in the levels of 5-aminopentanoate, acetate, butyrate and propionate, in subjects with pSjD compared to subjects in the NS-C group. Additionally, a significant increase in choline was found only in the age-restricted subset, and a significant decrease in fucose was found only in the whole study population in normalized data of saliva samples from the pSjD group compared to the NS-C group. Metabolite concentration data of saliva samples from all study participants, but not from the age-restricted subset, indicated significant increases in the levels of glucose, glycerol, taurine, and lactate in subjects with pSjD compared to controls. The study showed that NMR metabolomics can be implemented in defining salivary metabolic signatures that are associated with disease status, and can contribute to differential analysis between subjects with pSjD and those who are not affected with this disease, in the clinic.

Characterizing Sjögren-Associated Fatigue: A Distinct Phenotype from ME/CFS

Fatigue is the most commonly reported and debilitating extraglandular symptom of primary Sjögren's syndrome (pSS). Fatigue and exertional intolerance are hallmark symptoms of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). We aimed to characterize fatigue and further symptoms among pSS patients and to determine whether there is a symptom overlap in pSS and ME/CFS. In 19 patients with pSS, we assessed pSS symptom severity and disease activity via questionnaires as well as the Canadian Consensus Criteria (CCC) for ME/CFS. Hand grip strength (HGS) and levels of α1-, α2-, β1-, β2-, M3- and M4-receptor-autoantibodies were measured. A subgroup of pSS patients exhibited severe fatigue and had higher severity of pain (p = 0.045), depression (p = 0.021) and sleep disturbances (p = 0.020) compared to those with less fatigue. Four of eighteen pSS patients fulfilled the CCC. HGS parameters strongly correlated with fatigue severity (p < 0.05), but strength fully recovered one hour after exertion in contrast to ME/CFS. Levels of β1-, β2- and M4-receptor-autoantibodies were elevated and correlated significantly with disease activity assessed by the ESSDAI (p < 0.05), but not fatigue severity. Only a minor subgroup of pSS patients fulfills the CCC, and post exertional malaise (PEM) is atypical, as it is primarily triggered by mental/emotional but not physical exertion. HGS assessment is an objective measure to assess overall fatigue severity.

Phases and Natural History of Sjögren's Disease: A New Model for an Old Disease?

Sjögren's disease (SjD) is an archetypal and heterogenous autoimmune disorder that is characterized by exocrine glandular dysfunction. A proportion of patients develop severe extraglandular manifestations, such as cryoglobulinemia, and have an increased risk of lymphoma, both of which can adversely affect quality of life and occasionally mortality. As with most autoimmune disorders, the pathogenesis is poorly understood and difficult to predict, and, frustratingly, there is a lack of targeted therapies to cure this disease. We review the disease manifestations of SjD and propose a staged model for understanding the evolution of pathology. In longitudinal studies, most patients remain relatively stable in terms of their laboratory and clinical parameters. However, in the setting of various risk factors, a proportion of patients develop severe symptoms and/or lymphoma. We discuss potential underlying mechanisms for disease progression and the strengths and limitations of using a staged model to correlate the pathogenesis and spectrum of manifestations in SjD. Ultimately, understanding how and why some patients remain relatively stable, whereas others progress and develop florid systemic disease and a fraction develop lymphoma, is key to developing preventative and therapeutic treatments.

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.

CAR-Based Therapy for Autoimmune Diseases: A Novel Powerful Option

The pervasive application of chimeric antigen receptor (CAR)-based cellular therapies in the treatment of oncological diseases has long been recognized. However, CAR T cells can target and eliminate autoreactive cells in autoimmune and immune-mediated diseases. By doing so, they can contribute to an effective and relatively long-lasting remission. In turn, CAR Treg interventions may have a highly effective and durable immunomodulatory effect via a direct or bystander effect, which may have a positive impact on the course and prognosis of autoimmune diseases. CAR-based cellular techniques have a complex theoretical foundation and are difficult to implement in practice, but they have a remarkable capacity to suppress the destructive functions of the immune system. This article provides an overview of the numerous CAR-based therapeutic options developed for the treatment of immune-mediated and autoimmune diseases. We believe that well-designed, rigorously tested cellular therapies could provide a promising new personalized treatment strategy for a significant number of patients with immune-mediated disorders.

Anti-SSA/SSB-negative primary Sjögren's syndrome showing different clinical phenotypes: a retrospective study of 934 cases

BACKGROUND

Currently, only a few studies have described the general characteristics of patients with primary Sjögren's syndrome (pSS) who tested negatives for anti-SSA and anti-SSB antibodies. We aimed to further investigate the clinical characteristics of these patients in a large sample.

METHODS

Data from patients with pSS who were treated at a tertiary hospital in China between 2013 and 2022 were retrospectively analyzed. Clinical characteristics of the patients were compared between those with and without anti-SSA and anti-SSB antibody negativity. Factors associated with anti-SSA and anti-SSB negativity were identified by logistic regression analysis.

RESULTS

Overall, 934 patients with pSS were included in this study, among whom 299 (32.0%) tested negative for anti-SSA and anti-SSB antibodies. Compared with patients testing positive for anti-SSA or anti-SSB antibodies, that testing negative for the two antibodies had a lower proportion of females (75.3% vs. 90.6%, p < 0.001) and thrombocytopenia (6.7% vs. 13.6%, p = 0.002), but a higher proportion of abnormal Schirmer I tests (96.0% vs. 89.1%, p = 0.001) and interstitial lung disease (ILD) (59.2% vs. 28.8%, p = 0.001). Anti-SSA and anti-SSB negativity was positively associated with male sex (odds ratio [OR] = 1.86, 95% confidence interval [CI]: 1.05, 3.31), abnormal Schirmer I tests (OR = 2.85, 95% CI: 1.24, 6.53), and ILD (OR = 2.54, 95% CI: 1.67, 3.85). However, it was negatively related to thrombocytopenia (OR = 0.47, 95% CI: 0.24, 0.95).

CONCLUSION

Approximately one third of pSS patients had anti-SSA and anti-SSB negativity. pSS patients testing negative for anti-SSA and anti-SSB showed a higher risk of abnormal Schirmer I tests and ILD, but a lower risk of thrombocytopenia.

Quadriparesis and Broad Complex Tachycardia Secondary to Severe Hypokalaemia Induced by Distal Renal Tubular Acidosis as the Initial Manifestation of Sjogren's Syndrome

Sjogren's syndrome is an autoimmune disorder characterized by lymphocytic infiltration of exocrine glands that typically manifests as dysfunction of the lacrimal or salivary glands. About one-third of Sjogren's syndrome patients exhibit systemic symptoms. In one-third of Sjogren's syndrome cases, renal tubular acidosis (RTA) is present. Hypokalemia is the most prevalent electrolyte disorder in patients with distal RTA. A middle-aged female presented to the emergency department with a complaint of sudden-onset quadriparesis followed by shortness of breath. Her arterial blood gas analysis revealed severe hypokalaemia and metabolic acidosis. ECG revealed broad complex tachycardia, which resolved after starting potassium infusion. On evaluating the cause of normal anion gap metabolic acidosis and hypokalaemia, she was found to have distal renal tubular acidosis (RTA). Furthermore, on evaluating the cause of distal RTA, her SSA/Anti Ro and SSB/Anti La levels came out to be elevated, and a probable diagnosis of Sjogren's syndrome was made. Severe hypokalaemia leading to hypokalaemia quadriparesis and broad complex tachycardia as the initial manifestation of distal RTA due to Sjogren's syndrome is uncommon. Timely recognition and prompt replacement of potassium are key to improved outcomes. It is also important to note that Sjogren's syndrome should be taken into account even in the absence of sicca symptoms, like in our case.

The Autoimmune Rheumatic Disease Related Dry Eye and Its Association with Retinopathy

Dry eye disease is a chronic disease of the ocular surface characterized by abnormal tear film composition, tear film instability, and ocular surface inflammation, affecting 5% to 50% of the population worldwide. Autoimmune rheumatic diseases (ARDs) are systemic disorders with multi-organ involvement, including the eye, and play a significant role in dry eye. To date, most studies have focused on Sjögren's syndrome (one of the ARDs) since it manifests as two of the most common symptoms-dry eyes and a dry mouth-and attracts physicians to explore the relationship between dry eye and ARDs. Many patients complained of dry eye related symptoms before they were diagnosed with ARDs, and ocular surface malaise is a sensitive indicator of the severity of ARDs. In addition, ARD related dry eye is also associated with some retinal diseases directly or indirectly, which are described in this review. This review also summarizes the incidence, epidemiological characteristics, pathogenesis, and accompanying ocular lesions of ARD's related dry eye, emphasizing the potential role of dry eye in recognition and monitoring among ARDs patients.

Utility of repeat extractable nuclear antigen antibody testing: a retrospective audit

OBJECTIVES

Autoantibodies to ENA are frequently ordered during the workup of suspected autoimmune connective tissue diseases. There are no current guidelines for repeat test ordering. The objective of this study was to assess the utility of repeat ENA testing after an initial negative result.

METHODS

A retrospective study was conducted in a single, multicentre tertiary health network in Melbourne, Australia. Results of all ENA tests were extracted from the hospital laboratory information system. For patients who had a change in ENA result from negative to positive, clinical information was obtained from the hospital records regarding new diagnosis of an ANA-associated rheumatic disease (AARD).

RESULTS

A total of 23 438 ENA tests were performed in 19 603 patients from 29 July 2013 to 28 September 2020. In total, 20 918 (89.2%) were negative with 215 (0.9%) being equivocal. Of the 2305 positive tests, the most common ENA auto-antibody specificity detected was anti-Ro52 (1185, 51.4%). A total of 2636 of 19 603 patients (13.4%) had more than one ENA test performed during the study period. Of these, most (2523, 95.7%) had stable ENA results with no change compared with the first test. Only 53 patients (2.2%) had an ENA result that changed from negative to positive. Excluding patients with pre-existing rheumatic conditions and those under 18, there were five new AARDs found in the remaining 34 patients.

CONCLUSION

Repeat ENA test results rarely change or result in a new diagnosis of an AARD, with repeated testing only warranted if there is a change in clinical manifestations.

Autoantibody repertoire characterization provides insight into the pathogenesis of monogenic and polygenic autoimmune diseases

Autoimmune diseases vary in the magnitude and diversity of autoantibody profiles, and these differences may be a consequence of different types of breaks in tolerance. Here, we compared the disparate autoimmune diseases autoimmune polyendocrinopathy-candidiasis-ecto-dermal dystrophy (APECED), systemic lupus erythematosus (SLE), and Sjogren's syndrome (SjS) to gain insight into the etiology of breaks in tolerance triggering autoimmunity. APECED was chosen as a prototypical monogenic disease with organ-specific pathology while SjS and SLE represent polygenic autoimmunity with focal or systemic disease. Using protein microarrays for autoantibody profiling, we found that APECED patients develop a focused but highly reactive set of shared mostly anti-cytokine antibodies, while SLE patients develop broad and less expanded autoantibody repertoires against mostly intracellular autoantigens. SjS patients had few autoantibody specificities with the highest shared reactivities observed against Ro-52 and La. RNA-seq B-cell receptor analysis revealed that APECED samples have fewer, but highly expanded, clonotypes compared with SLE samples containing a diverse, but less clonally expanded, B-cell receptor repertoire. Based on these data, we propose a model whereby the presence of autoreactive T-cells in APECED allows T-dependent B-cell responses against autoantigens, while SLE is driven by breaks in peripheral B-cell tolerance and extrafollicular B-cell activation. These results highlight differences in the autoimmunity observed in several monogenic and polygenic disorders and may be generalizable to other autoimmune diseases.

Anti-vimentin antibodies are associated with higher severity of Sjögren's disease

Vimentin is a ubiquitously present Type III intermediate filament protein, often targeted by autoimmune responses in multiple rheumatic disorders. Although previous studies have reported anti-vimentin antibodies in Sjögren's disease (SjD) patients, the clinical significance of such antibodies is unknown. To address this issue, the presence of anti-vimentin antibodies was determined in serum samples from a well-characterized cohort of primary SjD patients, non-SjD Sicca, and healthy controls. The occurrence of anti-vimentin antibodies and their association with different clinical features of the disease were evaluated. Anti-vimentin antibodies were detected in 24% of primary SjD patients, compared to 4% in non-SjD sicca patients and 3% in healthy controls. In primary SjD patients, higher levels of anti-vimentin antibodies were significantly associated with reduced saliva and tear flow and severe ocular surface damage indicators. The anti-vimentin antibody levels did not show significant associations with the presence or absence of other autoantibodies like ANA, RF, and anti-Ro/La. Our data suggest that the anti-vimentin antibody specificity arises in a subset of primary SjD patients and is associated with oral and ocular features of the disease. Anti-vimentin can potentially serve as a novel biomarker for evaluating the severity of salivary and lacrimal gland dysfunction in primary SjD.

An Overview of the Dry Eye Disease in Sjögren's Syndrome Using Our Current Molecular Understanding

Sjögren's syndrome is a chronic and insidious auto-immune disease characterized by lymphocyte infiltration of exocrine glands. The patients typically present with ocular surface diseases related to dry eye and other systemic manifestations. However, due to the high prevalence of dry eye disease and the lack of objective and clinically reliable diagnostic tools, discriminating Sjögren's syndrome dry eye (SSDE) from non-Sjögren's syndrome dry eye (NSSDE) remains a challenge for clinicians. Diagnosing SS is important to improve the quality of life of patients through timely referral for systemic workups, as SS is associated with serious systemic complications such as lymphoma and other autoimmune diseases. The purpose of this article is to describe the current molecular understanding of Sjögren's syndrome and its implications for novel diagnostic modalities on the horizon. A literature review of the pre-clinical and clinical studies published between 2016 and 2022 was conducted. The SSDE pathophysiology and immunology pathways have become better understood in recent years. Novel diagnostic modalities, such as tear and saliva proteomics as well as exosomal biomarkers, provide hope on the horizon.

Targeting B cells and plasma cells in autoimmune diseases: From established treatments to novel therapeutic approaches

Autoimmune diseases are characterized by the recognition of self-antigens by the immune system, which leads to inflammation and tissue damage. B cells are directly and indirectly involved in the pathophysiology of autoimmunity, both via antigen-presentation to T cells and production of proinflammatory cytokines and/or autoantibodies. Consequently, B lineage cells have been identified as therapeutic targets in autoimmune diseases. B cell depleting strategies have proven beneficial in the treatment of rheumatoid arthritis (RA), systemic lupus erythematous (SLE), ANCA-associated vasculitis (AAV), multiple sclerosis (MS), and a wide range of other immune-mediated inflammatory diseases (IMIDs). However, not all patients respond to treatment or may not reach (drug-free) remission. Moreover, B cell depleting therapies do not always target all B cell subsets, such as short-lived and long-lived plasma cells. These cells play an active role in autoimmunity and in certain diseases their depletion would be beneficial to achieve disease remission. In the current review article, we provide an overview of novel strategies to target B lineage cells in autoimmune diseases, with the focus on rheumatic diseases. Both advanced therapies that have recently become available and more experimental treatments that may reach the clinic in the near future are discussed.

Polyautoimmunity in systemic lupus erythematosus: secondary Sjogren syndrome

BACKGROUND

Sjogren's syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration of the exocrine glands. It can be associated with other connective tissue diseases, including systemic lupus erythematosus (SLE).

OBJECTIVE

This study aimed to determine the incidence of secondary SS (sSS) in patients diagnosed with SLE (SLE-SS) and compare the clinical and serological features of SLE-SS to SLE only.

METHODS

A retrospective observational study including patients diagnosed with SLE (SLICC criteria) seen at the Rheumatology Department between 1990 and 2020 was performed. A total of 453 SLE patients were assessed for fulfilment of the criteria for SS using the European questionnaire and Schirmer test, fluorescein staining/non-stimulated whole-salivary flow, anti-Ro/La antibodies, and lip biopsy. Anti-Ro/SSA and anti-La/SSB antibodies and rheumatoid factor (RF) were measured at entry and at SS assessment. SLE-SS was defined according to the American-European Consensus Criteria (AECC). SLE-SS was defined as a case that initially only fulfilled SLE classification criteria but which exhibited disease progression during follow-up and then met classification criteria for sSS.

RESULTS

SLE-SS occurred in 11% of the SLE patients. In comparison to SLE-only patients, the SLE-SS group was older at inclusion and onset, and had a longer disease course. Sicca syndrome, oral ulcers, pulmonary involvement, and peripheral neuropathy were more frequent. Anti-SSA, anti-SSB, RF, and total IgG were higher in the SLE-SS group.

CONCLUSION

SLE-SS appears to be a subgroup of patients with distinct clinical and serologic features. The frequency of SLE-SS increases with age. Patients with SLE-SS have a higher frequency of oral ulcers, anti-Ro and anti-La antibodies, and a lower frequency of renal disease, anti-dsDNA antibodies, anti-SM, and lower C3 and C4 hypocomplementemia.

Impaired Treg-DC interactions contribute to autoimmunity in leukocyte adhesion deficiency type 1

Leukocyte adhesion deficiency type 1 (LAD-1) is a rare disease resulting from mutations in the gene encoding for the common β-chain of the β2-integrin family (CD18). The most prominent clinical symptoms are profound leukocytosis and high susceptibility to infections. Patients with LAD-1 are prone to develop autoimmune diseases, but the molecular and cellular mechanisms that result in coexisting immunodeficiency and autoimmunity are still unresolved. CD4+FOXP3+ Treg are known for their essential role in preventing autoimmunity. To understand the role of Treg in LAD-1 development and manifestation of autoimmunity, we generated mice specifically lacking CD18 on Treg (CD18Foxp3), resulting in defective LFA-1 expression. Here, we demonstrate a crucial role of LFA-1 on Treg to maintain immune homeostasis by modifying T cell-DC interactions and CD4+ T cell activation. Treg-specific CD18 deletion did not impair Treg migration into extralymphatic organs, but it resulted in shorter interactions of Treg with DC. In vivo, CD18Foxp3 mice developed spontaneous hyperplasia in lymphatic organs and diffuse inflammation of the skin and in multiple internal organs. Thus, LFA-1 on Treg is required for the maintenance of immune homeostasis.

TLR7 agonism accelerates disease in a mouse model of primary Sjögren's syndrome and drives expansion of T-bet+ B cells

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterized by chronic inflammation of exocrine tissue, resulting in loss of tears and saliva. Patients also experience many extra-glandular disease manifestations. Treatment for pSS is palliative, and there are currently no treatments available that target disease etiology. Previous studies in our lab demonstrated that MyD88 is crucial for pSS pathogenesis in the NOD.B10Sn-H2^b (NOD.B10) pSS mouse model, although the way in which MyD88-dependent pathways become activated in disease remains unknown. Based on its importance in other autoimmune diseases, we hypothesized that TLR7 activation accelerates pSS pathogenesis. We administered the TLR7 agonist Imiquimod (Imq) or sham treatment to pre-disease NOD.B10 females for 6 weeks. Parallel experiments were performed in age and sex-matched C57BL/10 controls. Imq-treated pSS animals exhibited cervical lymphadenopathy, splenomegaly, and expansion of TLR7-expressing B cells. Robust lymphocytic infiltration of exocrine tissues, kidney and lung was observed in pSS mice following treatment with Imq. TLR7 agonism also induced salivary hypofunction in pSS mice, which is a hallmark of disease. Anti-nuclear autoantibodies, including Ro (SSA) and La (SSB) were increased in pSS mice following Imq administration. Cervical lymph nodes from Imq-treated NOD.B10 animals demonstrated an increase in the percentage of activated/memory CD4+ T cells. Finally, T-bet⁺ B cells were expanded in the spleens of Imq-treated pSS mice. Thus, activation of TLR7 accelerates local and systemic disease and promotes expansion of T-bet-expressing B cells in pSS.

Neonatal lupus erythematosus - prevention is better than cure

Neonatal lupus erythematosus (NLE) is a congenital autoimmune condition in which the transplacental passage of immunoglobulin G (IgG) directed against auto-antigens causes clinical symptoms in the foetus or neonate. Anti-Ro/SS-A, anti-La/SS-B, and to a lesser extent, anti-U1RNP autoantibodies (aAbs) have the strongest association with NLE. However, ~ 50% of affected mothers are asymptomatic despite carrying those aAbs. The clinical picture of the disease is very diverse. Cardiac manifestations are the most severe, including congenital heart block (CHB), with a mortality rate of ~18%. Preventative therapy with hydroxychloroquine (HCQ) reduces the recurrence rate of CHB in subsequent pregnancies by ~50%.

Alteration of Mitochondrial DNA Copy Number and Increased Expression Levels of Mitochondrial Dynamics-Related Genes in Sjögren's Syndrome

Sjögren's syndrome (SS) is a chronic autoimmune multifactorial disease characterized by inflammation and lymphocytic infiltration of the exocrine glands. Several studies have highlighted the involvement of oxidative stress in this pathology, suggesting that it could induce mitochondrial dysfunctions. Mitochondria could have a role in inflammatory and immune processes. Since the mitochondrial DNA (mtDNA) copy number could change in response to physiological or environmental stimuli, this study aimed to evaluate possible alterations in the mtDNA copy number in SS. We have analyzed the amount of mtDNA in the peripheral blood of 74 SS patients and 61 healthy controls by qPCR. Then, since mitochondrial fusion and fission play a crucial role in maintaining the number of mitochondria, we investigated the expression variability of the genes most commonly involved in mitochondrial dynamics in a subgroup of SS patients and healthy controls. Interestingly, we observed a highly significant decrease in mtDNA copies in the SS patients compared to healthy controls (p = 1.44 × 10^-12). Expression levels of mitochondrial fission factor (MFF), mitofusin-1 (MFN1), and mitochondrial transcription factor A (TFAM) genes were analyzed, showing a statistically significant increase in the expression of MFF (p = 0.003) and TFAM (p = 0.022) in the SS patients compared to healthy controls. These results give further insight into the possible involvement of mitochondrial dysfunctions in SS disease.

Autoantibodies - enemies, and/or potential allies?

Autoantibodies are well known as potentially highly harmful antibodies which attack the host via binding to self-antigens, thus causing severe associated diseases and symptoms (e.g. autoimmune diseases). However, detection of autoantibodies to a range of disease-associated antigens has enabled their successful usage as important tools in disease diagnosis, prognosis and treatment. There are several advantages of using such autoantibodies. These include the capacity to measure their presence very early in disease development, their stability, which is often much better than their related antigen, and the capacity to use an array of such autoantibodies for enhanced diagnostics and to better predict prognosis. They may also possess capacity for utilization in therapy, in vivo. In this review both the positive and negative aspects of autoantibodies are critically assessed, including their role in autoimmune diseases, cancers and the global pandemic caused by COVID-19. Important issues related to their detection are also highlighted.

Distinct CD4+ T cell signature in ANA-positive young adult patients

Failure of immune tolerance can lead to autoantibody production resulting in autoimmune diseases, a broad spectrum of organ-specific or systemic disorders. Immune tolerance mechanisms regulate autoreactive T and B cells, yet some lymphocytes escape and promote autoantibody production. CD4+ T cell dysregulation, characterized by decreased or impaired regulatory cells (Tregs) and/or accumulation of memory and effector T cells such as TH17, plays a crucial role in the pathogenesis of these diseases. Antinuclear antibody (ANAs) testing is used as a first step for the diagnosis of autoimmune disorders, although most ANA-positive individuals do not have nor will develop an autoimmune disease. Studying the differences of T cell compartment among healthy blood donors, ANA-negative patients and ANA-positive patients, in which loss of tolerance have not led to autoimmunity, may improve our understanding on how tolerance mechanisms fail. Herein, we report that ANA-positive patients exhibit a distinct distribution of T cell subsets: significantly reduced frequencies of recent thymic emigrants (RTE) and naïve T cells, and significantly increased frequencies of central memory T cells, TH2 and TH17 cells; modulations within the T cell compartment are most profound within the 18-40 year age range. Moreover, CD4+ T cells in ANA-positive patients are metabolically active, as determined by a significant increase in mTORC1 and mTORC2 signals, compared to ANA-negative patients and healthy blood donors. No significant impairment of Treg numbers or pro-inflammatory cytokine production was observed. These results identify a unique T cell signature associated with autoantibody production in the absence of autoimmune disease.

Serum ANCA as Disease Biomarkers: Clinical Implications Beyond Vasculitis

Usually associated with autoimmune diseases, anti-neutrophil cytoplasmic antibodies are also detected in other conditions, such as infections, malignancies, and after intake of certain drugs. Even if the mechanisms of production and their pathogenic role have not been fully elucidated yet, ANCA are widely recognized as a clinically alarming finding due to their association with various disorders. While ANCA target several autoantigens, proteinase-3, and myeloperoxidase are the ones proved to be most frequently related to chronic inflammation and tissue damage in murine models. Albeit these autoantibodies could be present as an isolated observation without any implications, ANCA are frequently used in clinical practice to guide the diagnosis in a suspect of small vessel vasculitis. Conditions that should prompt the clinician to test ANCA status range from various forms of lung disease to renal or peripheral nervous system impairment. ANCA positivity in the presence of an autoimmune disease, especially rheumatoid arthritis, or connective tissue diseases, is frequently correlated with more clinical complications and treatment inefficacy, even in the absence of signs of vasculitis. For this reason, it has been postulated that ANCA could represent the final expression of an immune dysregulation rather than a pathogenic event responsible for organs damage. Recently, it has also been proposed that ANCA specificity (PR3 or MPO) could possibly define ANCA-associated vasculitides better than clinical phenotype. This review aims at summarizing the latest advancements in the field of ANCA study and clinical interpretation.

Biomarkers of lymphoma in Sjögren's syndrome: what's the latest?

INTRODUCTION

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease standing in the crossroads of autoimmunity and lymphomagenesis, characterized by chronic B-cell hyperactivity and ectopic lymphoid tissue neoformation, potentially driving lymphoid malignant transformation. Lymphoma development is considered the most serious complication of pSS.

AREAS COVERED: “

Old-classical" biomarkers (clinical, serological, hematological, and histological) validated in the past are analyzed under the perspective of recently published research. Biomarkers that have emerged during the last decade are subdivided to "old-new" and "newly proposed-novel" ones, including biomarkers pathophysiologically related to B-cell differentiation, lymphoid organization, and immune responses, identified in serum and tissue, both at genetic and protein level. Upcoming new imaging biomarkers, promising for further patient stratification, are also analyzed.

EXPERT OPINION

Salivary gland enlargement and cryoglobulinemia still remain the best validated "classical-old" biomarkers for lymphoma development. Though new biomarkers still need to be validated, some can be used for the identification of high-risk patients long before lymphoma diagnosis, some might be more relevant in distinct age subgroups, while others have an added value in the assessment of lymphoma remission or relapse. Future development of composite indices integrating old and recently proposed biomarkers could contribute to a more precise lymphoma prediction model.

Abnormal B cell glycosylation in autoimmunity: A new potential treatment strategy

Systemic lupus erythematosus (SLE) and primary Sjögren’s syndrome (pSS) are two autoimmune diseases characterised by the production of pathogenic autoreactive antibodies. Their aetiology is poorly understood. Nevertheless, they have been shown to involve several factors, such as infections and epigenetic mechanisms. They also likely involve a physiological process known as glycosylation. Both SLE T cell markers and pSS-associated autoantibodies exhibit abnormal glycosylation. Such dysregulation suggests that defective glycosylation may also occur in B cells, thereby modifying their behaviour and reactivity. This study aimed to investigate B cell subset glycosylation in SLE, pSS and healthy donors and to extend the glycan profile to serum proteins and immunoglobulins. We used optimised lectin-based tests to demonstrate specific glycosylation profiles on B cell subsets that were specifically altered in both diseases. Compared to the healthy donor B cells, the SLE B cells exhibited hypofucosylation, whereas only the pSS B cells exhibited hyposialylation. Additionally, the SLE B lymphocytes had more galactose linked to N-acetylglucosamine or N-acetylgalactosamine (Gal-GlcNAc/Gal-GalNAc) residues on their cell surface markers. Interestingly, some similar alterations were observed in serum proteins, including immunoglobulins. These findings indicate that any perturbation of the natural glycosylation process in B cells could result in the development of pathogenic autoantibodies. The B cell glycoprofile can be established as a preferred biomarker for characterising pathologies and adapted therapeutics can be used for patients if there is a correlation between the extent of these alterations and the severity of the autoimmune diseases.

Seronegative autoimmune diseases: A challenging diagnosis

Autoimmune diseases (AID) are increasingly prevalent conditions which comprise more than 100 distinct clinical entities that are responsible for a great disease burden worldwide. The early recognition of these diseases is key for preventing their complications and for tailoring proper management. In most cases, autoantibodies, regardless of their potential pathogenetic role, can be detected in the serum of patients with AID, helping clinicians in making a definitive diagnosis and allowing screening strategies for early -and sometimes pre-clinical- diagnosis. Despite their undoubted crucial role, in a minority of cases, patients with AID may not show any autoantibody, a condition that is referred to as seronegative AID. Suboptimal accuracy of the available laboratory tests, antibody absorption, immunosuppressive therapy, immunodeficiencies, antigen exhaustion, and immunosenescence are the main possible determinants of seronegative AID. Indeed, in seronegative AID, the diagnosis is more challenging and must rely on clinical features and on other available tests, often including histopathological evaluation and radiological diagnostic tests. In this review, we critically dissect, in a narrative fashion, the possible causes of seronegativity, as well as the diagnostic and management implications, in several AID including autoimmune gastritis, celiac disease, autoimmune liver disease, rheumatoid arthritis, autoimmune encephalitis, myasthenia gravis, Sjögren's syndrome, antiphospholipid syndrome, and autoimmune thyroid diseases.

Salivary gland function, development, and regeneration

Salivary glands produce and secrete saliva, which is essential for maintaining oral health and overall health. Understanding both the unique structure and physiological function of salivary glands, as well as how they are affected by disease and injury, will direct the development of therapy to repair and regenerate them. Significant recent advances, particularly in the OMICS field, increase our understanding of how salivary glands develop at the cellular, molecular, and genetic levels: the signaling pathways involved, the dynamics of progenitor cell lineages in development, homeostasis, and regeneration, and the role of the extracellular matrix microenvironment. These provide a template for cell and gene therapies as well as bioengineering approaches to repair or regenerate salivary function.

Analysis of TNFSF13B polymorphisms and BAFF expression in rheumatoid arthritis and primary Sjögren's syndrome patients

Background

The increased expression of B cell‐activating factor (BAFF) has been linked to autoantibody production in autoimmune diseases (ADs). The aim of this study was to investigate the association among TNFSF13B gene (OMIM: 603969) single nucleotide polymorphisms (SNPs), TNFSF13B mRNA, and soluble BAFF (sBAFF) expression in patients with rheumatoid arthritis (RA) and primary Sjögren's syndrome (pSS). The diagnostic value of sBAFF also was evaluated by the area under the curve (AUC) of receiver operating characteristic or receptor (ROC) curves.

Methods

Genotypes of the TNFSF13B rs9514827 (−2841 T > C), rs1041569 (−2701 A > T) and rs9514828 (−871 C > T) SNPs were determined by PCR‐RFLP assay. TNFSF13B mRNA and sBAFF expression were performed by RT‐qPCR and ELISA, respectively. The study included 320 RA patients, 101 pSS patients, and 309 healthy subjects (HS).

Results

The rs9514828 T allele and the TAT haplotype were associated with an increased risk to develop RA. In both ADs, the TNFSF13B mRNA levels were increased in comparison with HS. The rs9514828 (−871 C > T) polymorphism was associated with increased gene expression in RA patients. Also, sBAFF levels were higher in both ADs, however pSS patients showed the highest sBAFF levels. sBAFF showed higher diagnostic performance for pSS with an AUC of 0.968, with a similar accuracy of anti‐SSA/Ro antibody diagnosis (AUC = 0.974).

Conclusions

Our findings demonstrate that the TNFSF13B rs9514828 (−871 C > T) polymorphism is a risk factor for RA in the western Mexican population. sBAFF levels may be a potential diagnosis biomarker in pSS.

Dry eye in Sjögren's syndrome - characteristics and therapy

BACKGROUND

Sjögren's syndrome is an autoimmune disease, and its important feature is the lymphocyte infiltration of exocrine glands, including lacrimal glands. It contributes to defects of their activity and causes that one of the main manifestation of Sjögren's syndrome is dry eye. Unfortunately, the discrimination between dry eye related and non-related to Sjögren's syndrome is difficult at the initial stages of diseases. In addition, the available agents for the treatment of Sjögren's syndrome-related dry eye have limited efficacy.

AIM

The purpose of this study was to describe and emphasize differences between Sjögren's Syndrome-related dry eye and non-Sjögren's Syndrome-related dry eye together with the determination of novel therapeutic options for Sjögren's Syndrome-related dry eye.

METHOD

A review of the relevant papers describing characteristics of Sjögren's Syndrome-related dry eye and its therapy was conducted. This article is based on both pre-clinical and clinical evidences.

RESULTS

On the basis of our analysis, we indicated differences between Sjögren's Syndrome-related dry eye and non-Sjögren's Syndrome-related dry eye. Moreover, there are some novel markers that could be used in the diagnosis of Sjögren's Syndrome-related dry eye. In addition, expect artificial tear, other agents e.g. hydroxychloroquine can be effective in therapy of disease.

CONCLUSIONS

Sjögren's Syndrome-related dry eye is a disorder, whose diagnosis may be difficult and mistaken for non-Sjögren's Syndrome-related dry eye. However, Sjögren's Syndrome-related dry eye has some specific features. In addition, the development of newer and safer therapeutic agents for Sjögren's syndrome-related dry eye is needed, and therefore further clinical, randomized studies are necessary.

Preliminary Screening Questionnaire for Sjögren's Syndrome in the Rheumatology Setting

OBJECTIVE

Sjögren's syndrome (SS) is frequently undetected or misdiagnosed as other rheumatologic diseases. We aimed to develop an SS screening questionnaire for the rheumatology practice.

METHODS

We developed the Sjögren's Syndrome Screening Questionnaire (SSSQ) via secondary analysis of data from 974 participants referred by rheumatologists to the Sjögren's International Collaborative Clinical Alliance (SICCA) study. Participants answered 88 questions regarding symptoms, medical history, and demographics. They underwent ocular, dental, and serologic tests and were classified as SS or non-SS using the 2016 American College of Rheumatology/European League Against Rheumatism classification criteria. We conducted univariate and multivariate logistic regression to identify questions most discriminative of SS, from which we derived an individual's likelihood of SS ("SSSQ score").

RESULTS

Five questions were significantly discriminative of SS in the multivariate analysis (p < 0.05): (1) Can you eat a cracker without drinking a fluid/liquid? (no: odds ratio [OR], 1.39; 95% confidence interval [CI], 1.06-1.82]); (2) How would you describe your dental and oral health in general? (fair/poor: OR, 1.68; 95% CI, 1.04-2.75); (3) During the last week, have you experienced tearing? (none of the time: OR, 2.26; 95% CI, 1.23-4.34); (4) Are you able to produce tears? (no: OR, 1.62; 95% CI, 1.12-2.37); and (5) Do you currently smoke cigarettes? (no: OR, 2.83; 95% CI, 1.69-4.91). SSSQ score ≥7 (possible range, 0-11) distinguishes SS from non-SS patients with 64% sensitivity and 58% specificity (area under receiver operating characteristic curve, 0.65).

CONCLUSIONS

The SSSQ is a simple 5-item questionnaire designed to screen for SS in clinical practice, with a potential impact to reduce delays in diagnosis.

Plasmacytoid dendritic cells promote the pathogenesis of Sjögren's syndrome

Plasmacytoid dendritic cells (pDCs) produce type I interferons (IFNs) and promote pathogenesis of multiple autoimmune diseases. Autoimmune Sjögren's syndrome (SS) primarily affects salivary and lacrimal glands, causing their inflammation, destruction and dysfunction. pDCs and type I IFN activity are elevated in salivary glands of SS patients, and this study seeks to elucidate the in vivo actions of pDCs in SS pathogenesis using the non-obese diabetic (NOD) mouse model. We confirmed the type I IFN-dependency of SS development in female NOD mice and elevation of pDC-type I IFN in their submandibular glands (SMGs). We administered a pDC-depleting anti-BST2/CD317 antibody to female NOD mice from 4 to 7 weeks of age at the early stage of SS, and assessed SS pathologies at age 10 weeks, the time of disease onset. Depletion of pDCs impeded the development of SMG inflammation and secretory dysfunction. It drastically reduced the amount of type I IFN mRNA and the number of total leukocytes, and T- and B lymphocytes in SMGs. Gene expression analyses showed that pDC depletion markedly diminished SMG expression of IL-7, BAFF, TNF-α, IFN-γ, CXCL9, CXCL11, CD40, CD40L, Lt-α, Lt-β and NOS2. Hence, pDCs critically contribute to the development and onset of SS-like salivary gland exocrinopathy.