The role of virus infections in Sjögren’s syndrome

Cellular Metabolic Disorders in a Cohort of Patients with Sjogren's Disease

Metabolism disorders have been seen in multiple autoimmune diseases, including SLE and Sjogren's disease. The current studies were designed to evaluate mutations in genes involved in metabolism in a cohort of patients with Sjogren's disease, diagnosed from clinical criteria and the presence of antibodies to salivary gland antigens. Patients were from an Immunology clinic that follows a large population of patients with autoimmune and metabolic disorders. The patients included in these studies were patients who met the criteria for Sjogren's disease and for whom we were able to obtain genetic studies, sequencing of the mitochondrial DNA, and whole exome sequencing. There were 194 of these patients, and 192 had mutations in one or more gene involved in metabolism: 188 patients had mutations in mitochondrial respiratory chain genes, 17 patients had mutations in mitochondrial tRNA genes, 10 patients had mutations in mitochondrial DLOOP regions, 6 patients had mutations involved in carnitine transport, 6 patients had mutations in genes causing mitochondrial depletion, and 7 patients had glycogen storage diseases. In all cases, the treatment of the metabolic disorder led to symptomatic improvement in energy, exercise tolerance, gastrointestinal dysmotility, and the management of infections. In conclusion, metabolic disorders are common in patients with Sjogren's disease and may be one of the factors leading to the initiation of the disease. The treatment of patients with Sjogren's disease should include the treatment of the underlying/associated metabolic disorder.

Association of mitochondrial RNA expression levels in saliva and plasma with interferon signature gene expression and disease activity in patients with Sjögren disease

OBJECTIVE

To unveil the clinical implications of mitochondrial RNAs (mt-RNAs) in Sjögren disease (SjD), this study evaluated mt-RNA expression levels in the plasma and saliva of patients with SS and their association with SjD-related features.

METHODS

Plasma, saliva and/or peripheral blood mononuclear cells (PBMCs) were collected from 111 patients with SjD and 35 healthy controls (HCs), with 40 rheumatoid arthritis (RA) and 40 systemic lupus erythematosus (SLE) disease controls. The expression levels of mt-RNAs and interferon-stimulated genes (ISGs) were quantified by real-time PCR. Composite mt-RNA and ISG scores were calculated using logistic regression models. Their discriminative power was evaluated using receiver operating characteristic curve analyses, and correlations with clinical data were explored.

RESULTS

Altered mt-RNA expression in saliva or plasma and ISG expression in PBMCs were detected in patients with SjD, compared with HCs. Saliva and plasma mt-RNA scores showed better discriminative ability (area under the curve values=0.847 and 0.789, respectively) than ISG scores in distinguishing SjD from HCs. Plasma mt-RNA scores were significantly higher in patients with SjD than in those with RA and SLE (p<0.05). Saliva mt-RNA scores were positively associated with objective disease activity measures and Raynaud phenomenon in patients with SjD, whereas plasma mt-RNA scores did not show this association. RA and SLE disease activity correlated with plasma mt-RNA scores.

CONCLUSIONS

Extracellular mt-RNA burden is elevated in SjD, and mt-RNA scores effectively discriminated patients with SjD from HCs. Saliva mt-RNA levels were associated with SjD disease activity, suggesting their potential utility in disease monitoring and stratification of SjD.

The global prevalence of co-occurrence of Sjögren syndrome and Hepatitis C virus infection: A systematic review and meta-analysis

Sjögren syndrome (SS) is one of the lesser-known autoimmune diseases, with its mechanisms and pathogenesis not yet fully understood. However, recent studies indicate that infectious diseases, such as Hepatitis C virus (HCV) infection, may serve as risk factors for the development of SS. Accordingly, this study aimed to estimate the global co-occurrence rate of chronic HCV infection and SS. In this systematic review and meta-analysis, a comprehensive search for relevant studies was conducted in PubMed, Scopus, ISI Web of Science, and Google Scholar databases up to June 2024. Data from eligible studies were meticulously extracted and statistically analyzed using Comprehensive Meta-Analysis Software. The pooled prevalence of co-occurrence of HCV and SS was calculated using incidence rates with 95 % confidence intervals (CIs), and the association of chronic HCV infection with the development of SS was assessed via odds ratios (ORs) with 95 % CIs. Analysis of the articles retrieved from the databases showed 24 studies were considered eligible. The pooled estimate for the co-occurrence of HCV and SS was approximately 16.6 % (95 % CI: 8.8-28.9). Moreover, the results indicated that chronic HCV infection significantly increased the risk of developing SS (OR: 2.76; 95 % CI: 1.35-5.63). This study's findings revealed that HCV infection may play a role in the pathogenesis of and susceptibility to SS. Therefore, chronic HCV infection may trigger the onset of SS. However, further studies are required to confirm these results.

Analysis of the relationships between interferon-stimulated genes and anti-SSA/Ro 60 antibodies in primary Sjögren's syndrome patients via multiomics and machine learning methods

BACKGROUND

Primary Sjögren's syndrome (pSS) is a chronic systemic autoimmune disease characterized by lymphocyte infiltration of the exocrine glands. Interferon-stimulated genes (ISGs) are often upregulated in patients with pSS, and anti-SSA/Ro 60 antibodies are among the main items detected in pSS. However, the relationship between ISGs and anti-SSA/Ro 60 antibodies in pSS remains unclear. Therefore, our study aimed to explore the relationships between ISGs and anti-SSA/Ro 60 antibodies and identify key genes involved in pSS.

METHODS

Transcriptome sequencing and microarray data of PBMC, parotid and labial glands tissues from pSS patients (1341 samples) were downloaded from the GEO database and used in this analysis. A linear model was used to analyze the relationship between ISGs and anti-SSA/Ro 60 antibodies. ELISA was used to measure the levels of anti-SSA/Ro 60 antibodies in the whole blood of pSS patients. Machine learning methods were used to construct a diagnostic model, and further validation was conducted with external datasets and RT-qPCR.

RESULTS

After differential analysis of the PBMCs and tissues, 22 and 160 DEGs, respectively, were identified. There was a positive correlation between ISGs and anti-SSA/Ro 60 antibodies in the PBMCs of pSS patients, and there was a significant positive correlation between ISG expression in the PBMCs and tissues of pSS patients. The expression levels of ISGs were increased in the PBMCs and tissues of pSS patients with positive anti-SSA/Ro 60 antibody results, and the ESSDAI, focus scores and CD45 levels were increased. Finally, the expression of EPSTI1, EIF2AK2, IFI44, RSAD2, and OAS2 in PBMCs can be used to diagnose pSS.

CONCLUSION

In patients with pSS, a positive correlation was observed between ISGs and anti-SSA/Ro 60 antibodies. The expression of ISGs reflects the disease severity and pathology scores of pSS patients. Through bioinformatics analysis combined with our clinical data, we identified five key genes with potential diagnostic value for pSS.

Direct Inhibitory Effect of HTLV-1-Infected T Cells on the Production of Anti-Ro/SS-A Antibody by B Cells from Patients with Sjögren's Syndrome

The reasons for the low frequency of anti-Ro/SS-A antibody in patients with HTLV-1-associated myelopathy complicated with Sjögren's syndrome (SS) are unclear. In this study, we investigated whether HTLV-1-infected T cells can act directly on B cells and suppress B cells' production of antibodies, including anti-Ro/SS-A antibody. For this purpose, we established an in vitro T-cell-free B-cell antibody production system. The productions of total IgG and anti-cytomegalovirus IgG in B cells from healthy subjects and those of total IgG and anti-Ro/SS-A IgG in B cells from SS patients were significantly suppressed by the addition of HTLV-1-positive T-cell lines (MT-2 and HCT-5). Our analysis of co-cultured B cells identified no sign of HTLV-1 infection and revealed that MT-2 and HCT-5 cells act on the early stages of B-cell differentiation, not the activation stage. MT-2 and HCT-5 cells constitutively expressed CD70, ICAM-1, LAP (TGF-β), and PD-L1/2, but blocking monoclonal antibodies to these molecules or PD-L1/2 receptor PD-1 had no significant canceling effect on B-cell IgG production regarding their suppressive activity. Importantly, autologous CD4+CD25+CD127low Treg cells had no inhibitory effect on B-cell IgG production. These results demonstrate that HTLV-1-positive T cells can directly suppress B-cell antibody production through mechanisms that differ from Treg functions.

Possible involvement of Toll-like receptor 8-positive monocytes/macrophages in the pathogenesis of Sjögren's disease

Background

Sjögren's disease (SjD) is an autoimmune disease marked by lymphocytic infiltration of salivary and lacrimal glands, leading to glandular dysfunction, where CD4-positive helper T (Th) cells and their cytokines are crucial in the pathogenesis. Recent studies have demonstrated that Toll-like receptors (TLRs), particularly those recognizing immune complexes containing DNA and RNA, contribute to Th cell activation in various autoimmune diseases. This study explores the expression and function of these TLRs in SjD.

Methods

DNA microarray analysis of salivary gland tissue from six SjD patients and real-time PCR (n = 32) was used to identify overexpressed TLRs. Single-cell RNA sequencing (scRNA-seq) was performed using tissue lesions and integrated with published scRNA-seq data from tissues and peripheral blood mononuclear cells to examine gene expression in macrophages and monocytes. Finally, multi-color immunofluorescence staining was conducted to confirm TLR8 expression and function in SjD lesions (n = 19).

Results

DNA microarray analysis revealed the up-regulation of TLR8, along with other TLRs and innate immune response genes in SjD. Real-time PCR showed significant up-regulation of TLR7 and TLR8. TLR8 up-regulated in both analyses. In scRNA-seq analysis, the TLR8-expressing cluster comprised macrophages and monocytes, which also produced T cell activation genes like CD86. TLR8-positive macrophages infiltrated inflammatory sites and frequently expressed CD86 in quantitative imaging approaches.

Conclusions

These results suggest that infiltrating monocytes and macrophages may produce cytokines and chemokines through TLR8 stimulation, potentially enhancing B7 molecule expression, promoting the adaptive immune response, and contributing to SjD pathogenesis.

Cell therapy in Sjögren's syndrome: opportunities and challenges

Sjögren's syndrome (SS) is a chronic autoimmune disease caused by immune system disorders. The main clinical manifestations of SS are dry mouth and eyes caused by the destruction of exocrine glands, such as the salivary and lacrimal glands, and systemic manifestations, such as interstitial pneumonia, interstitial nephritis and vasculitis. The pathogenesis of this condition is complex. However, this has not been fully elucidated. Treatment mainly consists of glucocorticoids, disease-modifying antirheumatic drugs and biological agents, which can only control inflammation but not repair the tissue. Therefore, identifying methods to regulate immune disorders and repair damaged tissues is imperative. Cell therapy involves the transplantation of autologous or allogeneic normal or bioengineered cells into the body of a patient to replace damaged cells or achieve a stronger immunomodulatory capacity to cure diseases, mainly including stem cell therapy and immune cell therapy. Cell therapy can reduce inflammation, relieve symptoms and promote tissue repair and regeneration of exocrine glands such as the salivary glands. It has broad application prospects and may become a new treatment strategy for patients with SS. However, there are various challenges in cell preparation, culture, storage and transportation. This article reviews the research status and prospects of cell therapies for SS.

Immune and non-immune mediators in the fibrosis pathogenesis of salivary gland in Sjögren's syndrome

Sjögren's syndrome (SS) or Sjögren's disease (SjD) is a systemic autoimmune disease clinically manifested as sicca symptoms. This disease primarily impacts the functionality of exocrine glands, specifically the lacrimal and salivary glands (SG). SG fibrosis, an irreversible morphological change, is a severe consequence that occurs in the later stages of the disease due to sustained inflammation. However, the mechanism underlying SG fibrosis in SS remains under-investigated. Glandular fibrosis may arise from chronic sialadenitis, in which the interactions between infiltrating lymphocytes and epithelial cells potentially contributes to fibrotic pathogenesis. Thus, both immune and non-immune cells are closely involved in this process, while their interplays are not fully understood. The molecular mechanism of tissue fibrosis is partly associated with an imbalance of immune responses, in which the transforming growth factor-beta (TGF-β)-dependent epithelial-mesenchymal transition (EMT) and extracellular matrix remodeling are recently investigated. In addition, viral infection has been implicated in the pathogenesis of SS. Viral-specific innate immune response could exacerbate the autoimmune progression, resulting in overt inflammation in SG. Notably, post-COVID patients exhibit typical SS symptoms and severe inflammatory sialadenitis, which are positively correlated with SG damage. In this review, we discuss the immune and non-immune risk factors in SG fibrosis and summarize the evidence to understand the mechanisms upon autoimmune progression in SS.

Vitamin D in Primary Sjogren's Syndrome (pSS) and the Identification of Novel Single-Nucleotide Polymorphisms Involved in the Development of pSS-Associated Diseases

Sjögren's syndrome (SS) is a chronic autoimmune disorder characterised by lymphocytic infiltration of the exocrine glands, which leads to dryness of the eyes and mouth; systemic manifestations such as arthritis, vasculitis, and interstitial lung disease; and increased risks of lymphoma and cardiovascular diseases. SS predominantly affects women, with a strong genetic component linked to sex chromosomes. Genome-wide association studies (GWASs) have identified numerous single-nucleotide polymorphisms (SNPs) associated with primary SS (pSS), revealing insights into its pathogenesis. The adaptive and innate immune systems are crucial to SS's development, with viral infections implicated as environmental triggers that exacerbate autoimmune responses in genetically susceptible individuals. Moreover, recent research has highlighted the role of vitamin D in modulating immune responses in pSS patients, suggesting its potential therapeutic implications. In this review, we focus on the recently identified SNPs in genes like OAS1, NUDT15, LINC00243, TNXB, and THBS1, which have been associated with increased risks of developing more severe symptoms and other diseases such as fatigue, lymphoma, neuromyelitis optica spectrum disorder (NMOSD), dry eye syndrome (DES), and adverse drug reactions. Future studies should focus on larger, multi-ethnic cohorts with standardised protocols to validate findings and identify new associations. Integrating genetic testing into clinical practise holds promise for improving SS management and treatment strategies, enabling personalised interventions based on comprehensive genetic profiles. By focusing on specific SNPs, vitamin D, and their implications, future research can lead to more effective and personalised approaches for managing pSS and its complications.

Auto-immuno-deficiency syndromes

Autoimmune diseases constitute a broad, heterogenous group with many diverse and often overlapping symptoms. Even so, they are traditionally classified as either systemic, rheumatic diseases or organ-directed diseases. Several theories exist about autoimmune diseases, including defective self-recognition, altered self, molecular mimicry, bystander activation and epitope spreading. While there is no consensus about these theories, it is generally accepted that genetic, pre-disposing factors in combination with environmental factors can result in autoimmune disease. The relative contribution of genetic and environmental factors varies between diseases, as does the significance of individual contributing factors within related diseases. Among the genetic factors, molecules involved in antigen (Ag) recognition, processing, and presentation stand out (e.g., MHC I and II) together with molecules involved in immune signaling and regulation of cellular interactions (i.e., immuno-phenotypes). Also, various immuno-deficiencies have been linked to development of autoimmune diseases. Among the environmental factors, infections (e.g., viruses) have attracted most attention, but factors modulating the immune system have also been the subject of much research (e.g., sunlight and vitamin D). Multiple sclerosis currently stands out due to a very strong and proven association with Epstein-Barr virus infection, notably in cases of late infection and in cases of EBV-associated mononucleosis. Thus, a common picture is emerging that both systemic and organ-directed autoimmune diseases may appropriately be described as auto-immuno-deficiency syndromes (AIdeSs), a concept that emphasizes and integrates existing knowledge on the role of immuno-deficiencies and chronic infections with development of overlapping disease syndromes with variable frequencies of autoantibodies and/or autoreactive T cells. This review integrates and exemplifies current knowledge on the interplay of genetically determined immuno-phenotypes and chronic infections in the development of AIdeSs.

Evidence for Molecular Mimicry between SARS-CoV-2 and Human Antigens: Implications for Autoimmunity in COVID-19

As for other viral diseases, the mechanisms behind the apparent relationship between COVID-19 and autoimmunity are yet to be clearly defined. Molecular mimicry, the existence of sequence and/or conformational homology between viral and human antigens, could be an important contributing factor. Here, we review the accumulated evidence supporting the occurrence of mimicry between SARS-CoV-2 and human proteins. Both bioinformatic approaches and antibody cross-reactions have yielded a significant magnitude of mimicry events, far more common than expected to happen by chance. The clinical implication of this phenomenon is ample since many of the identified antigens may participate in COVID-19 pathophysiology or are targets of autoimmune diseases. Thus, autoimmunity related to COVID-19 may be partially explained by molecular mimicry and further research designed specifically to address this possibility is needed.

Exploring the crosstalk molecular mechanisms between IgA nephropathy and Sjögren's syndrome based on comprehensive bioinformatics and immunohistochemical analyses

IgA nephropathy (IgAN) and Sjogren's syndrome (SS) are two autoimmune diseases with undetermined etiology and related to abnormal activation of lymphocytes. This study aims to explore the crucial genes, pathways and immune cells between IgAN and SS. Gene expression profiles of IgAN and SS were obtained from the Gene Expression Omnibus and Nephroseq data. Differentially expressed gene (DEG) and weighted gene co-expression network analyses (WGCNA) were done to identify common genes. Enrichment analysis and protein-protein interaction network were used to explore potential molecular pathways and crosstalk genes between IgAN and SS. The results were further verified by external validation and immunohistochemistry (IHC) analysis. Additionally, immune cell analysis and transcription factor prediction were also conducted. The DEG analysis revealed 28 commonly up-regulated genes, while WGCNA identified 98 interactively positive-correlated module genes between IgAN and SS. The enrichment analysis suggested that these genes were mainly involved in the biological processes of response to virus and antigen processing and presentation. The external validation and IHC analysis identified 5 hub genes (PSMB8, PSMB9, IFI44, ISG15, and CD53). In the immune cell analysis, the effector memory CD8 T and T follicular helper cells were significantly activated, and the corresponding proportions showed positively correlations with the expressions of the 5 hub genes in the two autoimmune diseases. Together, our data identified the crosstalk genes, molecular pathways, and immune cells underlying the IgAN and SS, which provides valuable insights into the intricate mechanisms of these diseases and offers potential intervention targets.

Advances in cellular and molecular pathways of salivary gland damage in Sjögren's syndrome

Sjögren's Syndrome (SS) is an autoimmune disorder characterized by dysfunction of exocrine glands. Primarily affected are the salivary glands, which exhibit the most frequent pathological changes. The pathogenesis involves susceptibility genes, non-genetic factors such as infections, immune cells-including T and B cells, macrophage, dendritic cells, and salivary gland epithelial cells. Inflammatory mediators such as autoantibodies, cytokines, and chemokines also play a critical role. Key signaling pathways activated include IFN, TLR, BAFF/BAFF-R, PI3K/Akt/mTOR, among others. Comprehensive understanding of these mechanisms is crucial for developing targeted therapeutic interventions. Thus, this study explores the cellular and molecular mechanisms underlying SS-related salivary gland damage, aiming to propose novel targeted therapeutic approaches.

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.

Current developments and opportunities of pluripotent stem cells-based therapies for salivary gland hypofunction

Salivary gland hypofunction (SGH) caused by systemic disease, drugs, aging, and radiotherapy for head and neck cancer can cause dry mouth, which increases the risk of disorders such as periodontitis, taste disorders, pain and burning sensations in the mouth, dental caries, and dramatically reduces the quality of life of patients. To date, the treatment of SGH is still aimed at relieving patients' clinical symptoms and improving their quality of life, and is not able to repair and regenerate the damaged salivary glands. Pluripotent stem cells (PSCs), including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and extended pluripotent stem cells (EPSCs), are an emerging source of cellular therapies that are capable of unlimited proliferation and differentiation into cells of all three germ layers. In recent years, the immunomodulatory and tissue regenerative effects of PSCs, their derived cells, and paracrine products of these cells have received increasing attention and have demonstrated promising therapeutic effects in some preclinical studies targeting SGH. This review outlined the etiologies and available treatments for SGH. The existing efficacy and potential role of PSCs, their derived cells and paracrine products of these cells for SGH are summarized, with a focus on PSC-derived salivary gland stem/progenitor cells (SGS/PCs) and PSC-derived mesenchymal stem cells (MSCs). In this Review, we provide a conceptual outline of our current understanding of PSCs-based therapy and its importance in SGH treatment, which may inform and serve the design of future studies.

Herpesviridae, Neurodegenerative Disorders and Autoimmune Diseases: What Is the Relationship between Them?

Alzheimer's disease and Parkinson's disease represent the most common forms of cognitive impairment. Multiple sclerosis is a chronic inflammatory disease of the central nervous system responsible for severe disability. An aberrant immune response is the cause of myelin destruction that covers axons in the brain, spinal cord, and optic nerves. Systemic lupus erythematosus is an autoimmune disease characterized by alteration of B cell activation, while Sjögren's syndrome is a heterogeneous autoimmune disease characterized by altered immune responses. The etiology of all these diseases is very complex, including an interrelationship between genetic factors, principally immune associated genes, and environmental factors such as infectious agents. However, neurodegenerative and autoimmune diseases share proinflammatory signatures and a perturbation of adaptive immunity that might be influenced by herpesviruses. Therefore, they might play a critical role in the disease pathogenesis. The aim of this review was to summarize the principal findings that link herpesviruses to both neurodegenerative and autoimmune diseases; moreover, briefly underlining the potential therapeutic approach of virus vaccination and antivirals.

Prosthodontic implications of saliva and salivary gland dysfunction

PURPOSE

To provide a detailed overview of the fundamentals of saliva constituents and production. The review outlines the clinical manifestations as a consequence of salivary gland dysfunction and management strategies for patients with salivary gland dysfunction. Prosthodontic implications of saliva and salivary gland dysfunction are presented.

MATERIALS AND METHODS

English-language literature relating to saliva constituents, physiologic saliva production, clinical manifestations secondary to salivary gland dysfunction, salivary biomarkers, and management strategies were retrieved via electronic search. Relevant articles were summarized for this manuscript with a view toward providing pragmatic information.

RESULTS

Saliva is produced by three pairs of major and minor salivary glands. The major salivary glands, namely, the parotid, submandibular, and sublingual glands, contribute approximately 90% of saliva production. Saliva contains serous and mucinous secretions produced by different types of cells within salivary glands. Parasympathetic and sympathetic fibers innervate the major salivary glands, and upon stimulation, the parasympathetic innervation increases serous secretions, while the sympathetic innervation increases protein secretion. Stimulated saliva is mainly derived from the parotid glands which are composed of serous acini, while unstimulated saliva is mainly derived from the submandibular glands which are composed of mixed seromucous acini. As major salivary glands contribute the most to salivary flow, local or systemic factors influencing those glands can disrupt saliva production resulting in clinically significant oral manifestations.

CONCLUSION

This review provides a fundamental overview of saliva production. In addition, the review highlights the various clinical manifestations secondary to salivary gland dysfunction, explores salivary biomarkers for screening of systemic diseases, discusses management strategies for patients with salivary gland dysfunction, and outlines the prosthodontic implications of saliva and salivary gland dysfunction.

Genome-wide DNA methylation sequencing reveals epigenetic features and potential biomarkers of Sjögren syndrome

AIM

Sjögren syndrome (SS) is a slowly progressive, inflammatory, autoimmune disease. The aim of this study was to construct the DNA methylation profiles of whole blood of SS patients and healthy controls (HC), and to explore the role of differentially methylated genes in the pathogenesis of the disease.

METHODS

Whole-genome bisulfite sequencing was performed on three SS patients and four HC. The biological function of genes associated with differentially methylated regions (DMRs) was investigated using Gene Ontology functional analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis, using network-based key driver analysis (KDA) to find KDA genes. In clinical samples of SS patients and controls, the expression levels of KDA genes were validated by quantitative real-time polymerase chain reaction and immunohistochemical analysis. Moreover, the diagnostic value of KDA genes for SS was confirmed using receiver operating characteristic curves.

RESULTS

We identified 322 DMRs, annotated as 162 associated genes. Six genes were selected via the number of networks of KDA genes. Differential expression of genes such as human leukocyte antigen (HLA) class I, ADAR, and OAS2 was observed in patients' peripheral blood mononuclear cells and the minor salivary glands, which can be used as potential diagnostic biomarkers for SS.

CONCLUSION

Clinical sample validation suggested that HLA class I, ADAR, and OAS2 might play a role in the development of SS. Our study shows epigenetic regulatory mechanisms and potential disease markers associated with SS, which in turn will enable us to identify new therapeutic targets.

Analysis of Hepatitis D Virus in Minor Salivary Gland of Sjögren's Disease

Hepatitis delta virus (HDV) has been detected in the minor salivary gland (MSG) tissue of Sjögren's disease (SjD) patients in the absence of a hepatitis B virus (HBV) coinfection. Previous research has shown that HDV antigen (HDAg) expression can trigger an SjD-like phenotype in vivo, demonstrating a potential cause-and-effect relationship. We hypothesize that if HDV plays a role in the development of SjD, then HDV profiles may be correlated with disease manifestations. This retrospective study characterized HDV in a cohort of 48 SjD MSG samples collected between 2014 and 2021. Analyses of HDAg expression, including cell type and subcellular localization, in situ hybridization of HDV RNA, and comparative analyses with associated SjD and viral hepatitis clinical features, were conducted. HDAg was detected in MSG acinar, ductal, myoepithelial, and adipose cells and localized with the nuclei, cytoplasm, and mitochondria. In situ hybridization detected HDV genomic RNA localization in the MSG nuclei. A significant negative correlation was found between HDAg intensity and focal lymphocytic inflammation and in patients with both anti-SSA/Ro-52 and anti-SSA/Ro-60. In analyzing autoimmune disease comorbidities with SjD, it was found that SjD patients diagnosed with autoimmune thyroiditis and/or hypothyroidism were significantly more represented in the high HDAg intensity group compared to the negative and moderate HDAg intensity groups. No significant associations were detected between MSG-localized HDAg and liver enzymes or an evident HBV coinfection. This study has further confirmed that there is a nonhepatic reservoir for chronic HDV persistence in SjD-affected salivary gland tissue in a third independent SjD patient cohort. In addition, this study describes the unique colocalization of HDAg with mitochondria. The detection of HDV antigen and sequence within SjD-affected salivary gland tissue, and in the absence of an evident current or past HBV coinfection, warrants further investigation.

The Potential Role of SARS-CoV-2 Infection and Vaccines in Multiple Sclerosis Onset and Reactivation: A Case Series and Literature Review

The recent SARS-CoV-2 pandemic and related vaccines have raised several issues. Among them, the potential role of the viral infection (COVID-19) or anti-SARS-CoV-2 vaccines as causal factors of dysimmune CNS disorders, as well as the safety and efficacy of vaccines in patients affected by such diseases and on immune-active treatments have been analyzed. The aim is to better understand the relationship between SARS-CoV-2 infection/vaccines with dysimmune CNS diseases by describing 12 cases of multiple sclerosis/myelitis onset or reactivation after exposure to SARS-CoV-2 infection/vaccines and reviewing all published case reports or case series in which MS onset or reactivation was temporally associated with either COVID-19 (8 case reports, 3 case series) or anti-SARS-CoV-2 vaccines (13 case reports, 6 case series). All the cases share a temporal association between viral/vaccine exposure and symptoms onset. This finding, together with direct or immune-based mechanisms described both during COVID-19 and MS, claims in favor of a role for SARS-CoV-2 infection/vaccines in unmasking dysimmune CNS disorders. The most common clinical presentations involve the optic nerve, brainstem and spinal cord. The preferential tropism of the virus together with the presence of some host-related genetic/immune factors might predispose to the involvement of specific CNS districts.

Outline of Salivary Gland Pathogenesis of Sjögren's Syndrome and Current Therapeutic Approaches

Sjögren's syndrome (SS) is an autoimmune disease characterized by the involvement of exocrine glands such as the salivary and lacrimal glands. The minor salivary glands, from which tissue samples may be obtained, are important for the diagnosis, evaluation of therapeutic efficacy, and genetic analyses of SS. In the onset of SS, autoantigens derived from the salivary glands are recognized by antigen-presenting dendritic cells, leading to the activation of T and B cells, cytokine production, autoantibody production by plasma cells, the formation of ectopic germinal centers, and the destruction of salivary gland epithelial cells. A recent therapeutic approach with immune checkpoint inhibitors for malignant tumors enhances the anti-tumor activity of cytotoxic effector T cells, but also induces SS-like autoimmune disease as an adverse event. In the treatment of xerostomia, muscarinic agonists and salivary gland duct cleansing procedure, as well as sialendoscopy, are expected to ameliorate symptoms. Clinical trials on biological therapy to attenuate the hyperresponsiveness of B cells in SS patients with systemic organ involvement have progressed. The efficacy of treatment with mesenchymal stem cells and chimeric antigen receptor T cells for SS has also been investigated. In this review, we will provide an overview of the pathogenesis of salivary gland lesions and recent trends in therapeutic approaches for SS.

Platelet-Derived Microparticles and Autoimmune Diseases

Extracellular microparticles provide a means of cell-to-cell communication and can promote information exchanges between adjacent or distant cells. Platelets are cell fragments that are derived from megakaryocytes. Their main functions are to stop bleeding, regulate inflammation, and maintain the integrity of blood vessels. When platelets are activated, they can perform related tasks by secreting platelet-derived microparticles that contain lipids, proteins, nucleic acids, and even organelles. There are differences in the circulating platelet levels in many autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, antiphospholipid antibody syndrome, and Sjogren's syndrome. In this paper, the latest findings in the research field of platelet-derived microparticles are reviewed, including the potential pathogenesis of platelet-derived microparticles in various types of immune diseases, their potential as related markers, and for monitoring the progress and prognosis of disease treatment are expounded.

The Spectrum of Extraglandular Manifestations in Primary Sjögren's Syndrome

Extraglandular manifestations (EGMs) in primary Sjogren's syndrome (pSS) represent the clinical expression of the systemic involvement in this disease. EGMs are characterized by a wide heterogeneity; virtually any organ or system can be affected, with various degrees of dysfunction. The existing gaps of knowledge in this complex domain of extraglandular extension in pSS need to be overcome in order to increase the diagnostic accuracy of EGMs in pSS. The timely identification of EGMs, as early as from subclinical stages, can be facilitated using highly specific biomarkers, thus preventing decompensated disease and severe complications. To date, there is no general consensus on the diagnostic criteria for the wide range of extraglandular involvement in pSS, which associates important underdiagnosing of EGMs, subsequent undertreatment and progression to severe organ dysfunction in these patients. This review article presents the most recent basic and clinical science research conducted to investigate pathogenic mechanisms leading to EGMs in pSS patients. In addition, it presents the current diagnostic and treatment recommendations and the trends for future therapeutic strategies based on personalized treatment, as well as the latest research in the field of diagnostic and prognostic biomarkers for extraglandular involvement in pSS.