Increased salivary syndecan-1 level is associated with salivary gland function and inflammation in patients with Sjögren's syndrome

Serum levels of free light chains and syndecan-1 in patients with rheumatoid arthritis and systemic lupus erythematosus

OBJECTIVES

Systemic autoimmune rheumatic diseases (SARDs) are characterized by chronic inflammation. Reliable biomarkers are crucial for diagnosis, monitoring disease progression and therapeutic responses. This study explores serum syndecan-1 (SDC-1) as a biomarker for these conditions and its relationship with free light chain (FLC) levels.

METHODS

A retrospective analysis was performed on sera from 60 patients with rheumatoid arthritis (RA) and from 60 with systemic lupus erythematosus (SLE), alongside 50 healthy donors (HD). Κ- and λ- FLCs were determined by turbidimetric assay, while SDC-1 levels were determined by ELISA. Kruskal-Wallis test, Wilcoxon Mann-Whitney U test, multivariable linear regression and Spearman's correlation were employed to compare biomarker levels across groups and to explore correlations.

RESULTS

SDC-1, κ-FLC and λ-FLC were significantly increased in RA and SLE patients compared with HD (P < 0.001), while no significant differences in the κ/λ ratio were observed among the groups (P = 0.4). A significant difference in subject age was also identified. However, multivariate regression analysis indicated that RA and SLE are significantly associated with the levels of these markers, with minimal confounding by age. A significant correlation was observed separately in all groups between the FLC markers. Conversely, no correlation was detected between SDC-1 and FLCs, nor between these markers and age or disease activity indices.

CONCLUSION

Elevated serum levels of FLCs and SDC-1 in RA and SLE patients compared with HD underscore their potential as biomarkers for SARDs. The findings also suggest sustained plasma cell activation, supporting the multifaceted role of SDC-1 in the pathogenesis of SARDs.

Syndecan-1 Plays a Role in the Pathogenesis of Sjögren's Disease by Inducing B-Cell Chemotaxis through CXCL13-Heparan Sulfate Interaction

In Sjögren's disease (SjD), the salivary glandular epithelial cells can induce the chemotaxis of B cells by secreting B-cell chemokines such as C-X-C motif chemokine ligand 13 (CXCL13). Syndecan-1 (SDC-1) is a major transmembrane heparan sulfate proteoglycan (HSPG) predominantly expressed on epithelial cells that binds to and regulates heparan sulfate (HS)-binding molecules, including chemokines. We aimed to determine whether SDC-1 plays a role in the pathogenesis of SjD by acting on the binding of HS to B-cell chemokines. To assess changes in glandular inflammation and SDC-1 concentrations in the submandibular gland (SMG) and blood, female NOD/ShiLtJ and sex- and age-matched C57BL/10 mice were used. In the SMG of NOD/ShiLtJ mice, inflammatory responses were identified at 8 weeks of age, but increased SDC-1 concentrations in the SMG and blood were observed at 6 weeks of age, when inflammation had not yet started. As the inflammation of the SMG worsened, the SDC-1 concentrations in the SMG and blood increased. The expression of the CXCL13 and its receptor C-X-C chemokine receptor type 5 (CXCR5) began to increase in the SMG at 6 weeks of age and continued until 12 weeks of age. Immunofluorescence staining in SMG tissue and normal murine mammary gland cells confirmed the co-localization of SDC-1 and CXCL13, and SDC-1 formed a complex with CXCL13 in an immunoprecipitation assay. Furthermore, NOD/ShiLtJ mice were treated with 5 mg/kg HS intraperitoneally thrice per week for 6-10 weeks of age, and the therapeutic effects in the SMG were assessed at the end of 10 weeks of age. NOD/ShiLtJ mice treated with HS showed attenuated salivary gland inflammation with reduced B-cell infiltration, germinal center formation and CXCR5 expression. These findings suggest that SDC-1 plays a pivotal role in the pathogenesis of SjD by binding to CXCL13 through the HS chain.

Effect of miR-21 in mesenchymal stem cells-derived extracellular vesicles behavior

BACKGROUND

A challenging new branch of research related to aging-associated diseases is the identification of miRNAs capable of modulating the senescence-associated secretory phenotype (SASP) which characterizes senescent cells and contributes to driving inflammation.

METHODS

Mesenchymal stem cells (MSC) from human umbilical cord stroma were stable modified using lentivirus transduction to inhibit miR-21-5p and shotgun proteomic analysis was performed in the MSC-derived extracellular vesicles (EV) to check the effect of miR-21 inhibition in their protein cargo. Besides, we studied the paracrine effect of those modified extracellular vesicles and also their effect on SASP.

RESULTS

Syndecan-1 (SDC1) was the most decreased protein in MSC-miR21--derived EV, and it was involved in inflammation and EV production. MSC-miR21--derived EV were found to produce a statistically significant inhibitory effect on SASP and inflammaging markers expression in receptor cells, and in the opposite way, these receptor cells increased their SASP and inflammaging expression statistically significantly when treated with MSC-miR-21+-derived EV.

CONCLUSION

This work demonstrates the importance of miR-21 in inflammaging and its role in SASP through SDC1.

CD138 Is Expressed in Different Entities of Salivary Gland Cancer and Their Lymph Node Metastases and Therefore Represents a Potential Therapeutic Target

Advanced salivary gland carcinomas (SGC) often lack therapeutic options. Agents targeting CD138 have recently shown promising results in clinical trials for multiple myeloma and a preclinical trial for triple-negative breast cancer. Immunohistochemistry for CD138 was performed for all patients who had undergone primary surgery for SGC with curative intent. Findings were validated using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging. Overall, 111 primary SGC and 13 lymph node metastases from salivary duct carcinomas (SaDu) were evaluated. CD138 expression was found in 60% of all SGC with differing expression across entities (p < 0.01). A mean of 25.2% of the tumor cells in mucoepidermoid carcinoma (MuEp) were positive, followed by epithelial-myoepithelial carcinoma (20.9%), acinic cell carcinoma (16.0%), and SaDu (15.2%). High-/intermediate-grade MuEp showed CD138 expression in a mean of 34.8% of tumor cells. For SaDu, lymph node metastases showed CD138 expression in a mean of 31.2% of tumor cells which correlated with CD138 expression in their primaries (p = 0.01; Spearman’s ρ = 0.71). MALDI-MS imaging confirmed the presence of the CD138 protein in SGC. No significant association was found between clinicopathological data, including progression-free survival (p = 0.50) and CD138 expression. CD138 is expressed in the cell membrane of different entities of SGC and SaDu lymph node metastases and therefore represents a potential target for CD138 targeting drugs.

Fc receptors gone wrong: A comprehensive review of their roles in autoimmune and inflammatory diseases

Systemic autoimmune and inflammatory diseases have a complex and only partially known pathophysiology with various abnormalities involving all the components of the immune system. Among these components, antibodies, and especially autoantibodies are key elements contributing to autoimmunity. The interaction of antibody fragment crystallisable (Fc) and several distinct receptors, namely Fc receptors (FcRs), have gained much attention during the recent years, with possible major therapeutic perspectives for the future. The aim of this review is to comprehensively describe the known roles for FcRs (activating and inhibitory FcγRs, neonatal FcR [FcRn], FcαRI, FcεRs, Ro52/tripartite motif containing 21 [Ro52/TRIM21], FcδR, and the novel Fc receptor-like [FcRL] family) in systemic autoimmune and inflammatory disorders, namely rheumatoid arthritis, Sjögren's syndrome, systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies, mixed connective tissue disease, Crohn's disease, ulcerative colitis, immunoglobulin (Ig) A vasculitis, Behçet's disease, Kawasaki disease, IgG4-related disease, immune thrombocytopenia, autoimmune hemolytic anemia, antiphospholipid syndrome and heparin-induced thrombocytopenia.

Anti-Ro60 and anti-Ro52/TRIM21: Two distinct autoantibodies in systemic autoimmune diseases

As iconic and important diagnostic autoantibodies, anti-Ro60 and anti-Ro52/tri-partite motif-containing 21 (TRIM21) make a common appearance in a number of systemic autoimmune disorders such as systemic lupus erythematosus (SLE). These autoantibodies often co-exist together; yet despite their close relationship, there is no evidence that they are physically linked and probably reflect a convergence of separate processes of failed immunological tolerance. Confusingly, they are sometimes classed together as the "SSA" or "Ro" autoantibody system without clear distinction between the two. In this Short Communication, we discuss the diagnostic merits for separate detection and reporting of these two autoantibodies, and discuss avenues for future research. Indeed, further insight into their fascinating origins and pathogenic roles in autoimmunity will surely shed light on how we can prevent and treat devastating autoimmune disorders.