Salivary and serum soluble interleukin-2 receptor in primary Sjögren's syndrome

Impaired activation of STAT5 upon IL-2 stimulation in Tregs and elevated sIL-2R in Sjögren's syndrome

Background

Interleukin-2 (IL-2) and the high-affinity IL-2 receptor (IL-2R) are essential for the survival of regulatory T cells (Tregs) which are the main players in immune tolerance and prevention of autoimmune diseases. Sjögren’s syndrome (SS) is a chronic autoimmune disease predominantly affecting women and is characterised by sicca symptoms including oral and ocular dryness. The aim of this study was to investigate an association between IL-2R and Treg function in patients with SS of different severity defined by the salivary flow rate.

Methods

In a cross-sectional study, we determined plasma soluble IL-2R (sIL-2R) levels in women with SS (n=97) and healthy females (n=50) using ELISA. A subset of those (n=51) was screened for Treg function measured by the STAT5 signalling response to IL-2 using phospho-flow cytometry.

Results

We found that elevated plasma levels of sIL-2R were positively associated with the severity of SS reflected by a pathologically low salivary flow. Phospho-flow analysis revealed that patients with SS have a significantly lower frequency of pSTAT5⁺ Tregs upon IL-2 stimulation compared with healthy individuals, while the frequency of Tregs and pSTAT5 in conventional T cells remained unchanged. In addition, we observed more pSTAT5⁺ Tregs at baseline in patients with SS, which is significantly associated with seropositivity and elevated sIL-2R.

Conclusions

Our data indicates that Tregs have a weakened immunosuppressive function in patients with SS due to impaired IL-2/IL-2R signalling capacity. This could mediate lymphocytic infiltration into salivary glands inducing sicca symptoms. We believe that sIL-2R could act as a useful indicator for SS and disease severity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02769-y.

Immunophenotypes and clinical features of lymphocytes in the labial gland of primary Sjogren's syndrome patients

Objective

To investigate consistency of lymphocyte immunophenotype between labial gland and peripheral blood in patients with primary Sjogren's syndrome (pSS).

Methods

Seventy‐one pSS patients and 35 patients with maxillofacial trauma were included in the study. Based on the ratio of CD20 to CD3 in labial gland from 71 pSS patients, they were divided into the high and (n = 48) and low CD20 expression group (n = 23). Lymphocyte immunophenotypes in labial glands, course of disease, erythrocyte sedimentation rate (ESR), C‐reactive protein, immunoglobulin, and complement levels were analyzed.

Results

In the labial gland, the levels of IgG, IgA, IgM, and C3c were higher, but C1q was lower in the pSS group than in the control group (all P < .05). CD20 was detected in labial gland samples of all pSS patients, in which CD3 was positive in 66 (93.0%) patients, and negative in 5 (7.0%). The plasma levels of IgG, IgA, IgM, and CRP, and ESR were higher, but serum C4 level was lower in pSS patients than in the control group (all P < .01). Serum IgG level, ESR, and labial gland CD20 were higher in the high CD20 expression group than the low expression group (all P < .05).

Conclusion

Primary Sjogren's syndrome patients had a higher expression of CD20 positive infiltrating lymphocytes of the labial gland, accompanied with the changes of immunoglobulins, and complements in both the labial gland and peripheral blood.

Human saliva proteome analysis and disease biomarker discovery

Human saliva is an attractive body fluid for disease diagnosis and prognosis because saliva testing is simple, safe, low-cost and noninvasive. Comprehensive analysis and identification of the proteomic content in human whole and ductal saliva will not only contribute to the understanding of oral health and disease pathogenesis, but also form a foundation for the discovery of saliva protein biomarkers for human disease detection. In this article, we have summarized the proteomic technologies for comprehensive identification of proteins in human whole and ductal saliva. We have also discussed potential quantitative proteomic approaches to the discovery of saliva protein biomarkers for human oral and systemic diseases. With the fast development of mass spectrometry and proteomic technologies, we are enthusiastic that saliva protein biomarkers will be developed for clinical diagnosis and prognosis of human diseases in the future.

Conventional therapy of Sjogren's syndrome

Sjogren's syndrome (SS) is a chronic autoimmune disorder affecting mainly middle-aged women. It is characterized by lymphocytic infiltration and destruction of the exocrine glands (mainly the salivary and lacrimal glands), resulting in dry mouth and eyes. Symptoms of SS are chronic and sometimes devastating, compromising the quality of life at a major extent. Despite its autoimmune nature, evidence for the use of immunosuppressive agents, which are the mainstay of therapy of diseases of autoimmune origin, is limited. Keratoconjunctivitis sicca (KCS), the main ocular manifestation of SS, is managed with tear substitutes, as well as local and systemic stimulators of tear secretion and supportive surgical procedures. Management of oral manifestations includes intense oral hygiene, prevention and treatment of oral infections, use of saliva substitutes, and local and systematic stimulation of salivary secretion. Cholinergic agents, such as pilocarpine and cevimeline are the cornerstone of current therapy in SS. Corticosteroids, cyclophoshamide, and nucleoside analogues are reserved for severe extraglandular manifestations of SS. The role of anti-B-cell therapy is a promising option for glandular and extraglandular manifestations of the disease, as well as for the management of SS-associated lymphoma.

Salivary proteomic and genomic biomarkers for primary Sjögren's syndrome

OBJECTIVE

To identify a panel of protein and messenger RNA (mRNA) biomarkers in human whole saliva (WS) that may be used in the detection of primary Sjögren's syndrome (SS).

METHODS

Mass spectrometry and expression microarray profiling were used to identify candidate protein and mRNA biomarkers of primary SS in WS samples. Validation of the discovered mRNA and protein biomarkers was also demonstrated using real-time quantitative polymerase chain reaction and immunoblotting techniques.

RESULTS

Sixteen WS proteins were found to be down-regulated and 25 WS proteins were found to be up-regulated in primary SS patients compared with matched healthy control subjects. These proteins reflected the damage of glandular cells and inflammation of the oral cavity system in patients with primary SS. In addition, 16 WS peptides (10 up-regulated and 6 down-regulated in primary SS) were found at significantly different levels (P < 0.05) in primary SS patients and controls. Using stringent criteria (3-fold change; P < 0.0005), 27 mRNA in saliva samples were found to be significantly up-regulated in the primary SS patients. Strikingly, 19 of 27 genes that were found to be overexpressed were interferon-inducible or were related to lymphocyte filtration and antigen presentation known to be involved in the pathogenesis of primary SS.

CONCLUSION

Our preliminary study has indicated that WS from patients with primary SS contains molecular signatures that reflect damaged glandular cells and an activated immune response in this autoimmune disease. These candidate proteomic and genomic biomarkers may improve the clinical detection of primary SS once they have been further validated. We also found that WS contains more informative proteins, peptides, and mRNA, as compared with gland-specific saliva, that can be used in generating candidate biomarkers for the detection of primary SS.

The diagnostic applications of saliva--a review

This review examines the diagnostic application of saliva for systemic diseases. As a diagnostic fluid, saliva offers distinctive advantages over serum because it can be collected non-invasively by individuals with modest training. Furthermore, saliva may provide a cost-effective approach for the screening of large populations. Gland-specific saliva can be used for diagnosis of pathology specific to one of the major salivary glands. Whole saliva, however, is most frequently used for diagnosis of systemic diseases, since it is readily collected and contains serum constituents. These constituents are derived from the local vasculature of the salivary glands and also reach the oral cavity via the flow of gingival fluid. Analysis of saliva may be useful for the diagnosis of hereditary disorders, autoimmune diseases, malignant and infectious diseases, and endocrine disorders, as well as in the assessment of therapeutic levels of drugs and the monitoring of illicit drug use.