The future of biologic agents in the treatment of Sjögren's syndrome

Dental follicle mesenchymal stem cells ameliorated glandular dysfunction in Sjögren's syndrome murine model

OBJECTIVE

Dental mesenchymal stem cells (MSCs) are potential for use in tissue regeneration in inflammatory diseases due to their rapid proliferating, multilineage differentiation, and strong anti-inflammatory features. In the present study, immunoregulatory and glandular tissue regeneration effects of the dental follicle (DF)MSCs in Sjögren's Syndrome (SS) were investigated.

METHODS

Dental follicle (DF) tissues were obtained from healthy individuals during tooth extraction, tissues were digested enzymatically and DFMSCs were cultured until the third passage. DFMSCs were labeled with Quantum dot 655 for cell tracking analysis. The induction of the SS mouse model was performed by the injection of Ro60-273-289 peptide intraperitoneally. DFMSCs were injected intraperitoneally, or into submandibular, or lacrimal glands. Splenocytes were analyzed for intracellular cytokine (IFN-γ, IL-17, IL-10) secretion in T helper cells, lymphocyte proliferation, and B lymphocyte subsets. Histologic analysis was done for submandibular and lacrimal glands with hematoxylin-eosin staining for morphologic examination.

RESULTS

The systemic injection of DFMSCs significantly reduced intracellular IFN-γ and IL-17 secreting CD4+ T cells in splenocytes (p<0.05), and decreased inflammatory cell deposits and fibrosis in the glandular tissues. DFMSCs differentiated to glandular epithelial cells in submandibular and lacrimal injections with a significant reduction in lymphocytic foci. The results showed that few amounts of DFMSCs were deposited in glandular tissues when applied intraperitoneally, while high amounts of DFMSCs were located in glandular tissues and differentiated to glandular epithelial cells when applied locally in SS murine model.

CONCLUSION

DFMSCs have the potential for the regulation of Th1, Th17, and Treg balance in SS, and ameliorate glandular dysfunction. DFMSCs can be a beneficial therapeutic application for SS.

Type I Interferons in the Pathogenesis and Treatment of Autoimmune Diseases

Type I interferons (IFN-Is) are a very important group of cytokines that are produced by innate immune cells but also act on adaptive immune cells. IFN-Is possess antiviral, antitumor, and anti-proliferative effects, as well are associated with the initiation and maintenance of autoimmune disorders. Studies have shown that aberrantly expressed IFN-Is and/or type I IFN-inducible gene signatures in the serum or tissues of patients with autoimmune disorders are linked to their pathogenesis, clinical manifestations, and disease activity. Type I interferonopathies with mutations in genes impacting the type I IFN signaling pathway have shown symptoms and characteristics similar to those of systemic lupus erythematosus (SLE). Furthermore, both interventions in animal models and clinical trials of therapies targeting the type I IFN signaling pathway have shown efficacy in the treatment of autoimmune diseases. Our review aims to summarize the functions and targeted therapies (as well as clinical trials) of IFN-Is in both adult and pediatric autoimmune diseases, such as SLE, pediatric SLE (pSLE), rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), juvenile dermatomyositis (JDM), Sjögren syndrome (SjS), and systemic sclerosis (SSc), discussing the potential abnormal regulation of transcription factors and epigenetic modifications and providing a potential mechanism for pathogenesis and therapeutic strategies for future clinical use.

The impact of sex and gender on immunotherapy outcomes

Immunotherapies are often used for the treatment, remission, and possible cure of autoimmune diseases, infectious diseases, and cancers. Empirical evidence illustrates that females and males differ in outcomes following the use of biologics for the treatment of autoimmune diseases, e.g., rheumatoid arthritis (RA), infectious diseases, e.g., influenza, and solid tumor cancers. Females tend to experience more adverse reactions than males following the use of a class of biologics referred to as immunotherapies. For immunotherapies aimed at stimulating an immune response, e.g., influenza vaccines, females develop greater responses and may experience greater efficacy than males. In contrast, for immunotherapies that repress an immune response, e.g., tumor necrosis factor (TNF) inhibitors for RA or checkpoint inhibitors for melanoma, the efficacy is reportedly greater for males than females. Despite these differences, discrepancies in reporting differences between females and males exist, with females have been historically excluded from biomedical and clinical studies. There is a critical need for research that addresses the biological (i.e., sex) as well as sociocultural (i.e., gender) causes of male-female disparities in immunotherapy responses, toxicities, and outcomes. One-size-fits-all approaches to immunotherapies will not work, and sex/gender may contribute to variable treatment success, including adherence, in clinical settings.

Xerostomia: current streams of investigation

Xerostomia is the subjective feeling of dry mouth, and it is often related to salivary hypofunction. Besides medication-related salivary hypofunction, Sjögren syndrome and head-and-neck radiation are two common etiologies that have garnered considerable attention. Approaches to treating and/or preventing salivary hypofunction in patients with these conditions will likely incorporate gene therapy, stem cell therapy, and tissue engineering. Advances in these disciplines are central to current research in the cure for xerostomia and will be key to eventual treatment.

Type I IFN-mediated regulation of IL-1 production in inflammatory disorders

Although contributing to inflammatory responses and to the development of certain autoimmune pathologies, type I interferons (IFNs) are used for the treatment of viral, malignant, and even inflammatory diseases. Interleukin-1 (IL-1) is a strongly pyrogenic cytokine and its importance in the development of several inflammatory diseases is clearly established. While the therapeutic use of IL-1 blocking agents is particularly successful in the treatment of innate-driven inflammatory disorders, IFN treatment has mostly been appreciated in the management of multiple sclerosis. Interestingly, type I IFNs exert multifaceted immunomodulatory effects, including the reduction of IL-1 production, an outcome that could contribute to its efficacy in the treatment of inflammatory diseases. In this review, we summarize the current knowledge on IL-1 and IFN effects in different inflammatory disorders, the influence of IFNs on IL-1 production, and discuss possible therapeutic avenues based on these observations.

Treatment of primary Sjögren's syndrome with anti-CD20 therapy (rituximab). A feasible approach or just a starting point?

INTRODUCTION

In vitro and in vivo experimental data have suggested new immunopathogenic mechanisms in primary Sjögren's syndrome (pSS). The availability of targeted treatment modalities has opened new ways to selectively target these mechanistic pathways in vivo. Amongst these new treatment modalities, monoclonal antibodies specific for the B-cell surface molecule CD20 have been shown to be the most promising treatment option to date.

AREAS COVERED

A search of the Pubmed, MEDLINE, EMBASE, Cochrane and Ovid databases was performed to review literature on the efficacy and safety profile of anti-CD20 therapy in pSS patients.

EXPERT OPINION

A single course of the chimeric humanized anti-CD20 antibody rituximab was effective in reducing disease activity in pSS patients for about six to nine months. Retreatment of responders resulted in a similar effect to initial treatment. When combined with corticosteroids during infusion, rituximab was shown to be a safe drug to administer. Thus, anti-CD20 therapy can be considered an effective treatment option in pSS patients. However, large randomized controlled trials with anti-CD20 therapy, for example rituximab, are warranted in order to: 1) assess long-term effects of such treatment, 2) determine which pSS patients will benefit most from anti-CD20 treatment and 3) assess which retreatment schedule should be followed.

Preclinical validation of salivary biomarkers for primary Sjögren's syndrome

OBJECTIVE

Sjögren’s syndrome (SS) is a systemic autoimmune disease with a variety of presenting symptoms that may delay its diagnosis. We previously discovered a number of candidate salivary biomarkers for primary SS using both mass spectrometry and expression microarray analysis. In the current study, we aimed to verify these candidate biomarkers in independent patient populations and to evaluate their predictive values for primary SS detection.

METHODS

In total, 34 patients with primary SS, 34 patients with systemic lupus erythematosus (SLE), and 34 healthy individuals were enrolled for the validation studies. Salivary protein biomarkers were measured using either Western blotting or enzyme-linked immunosorbent assay, and the messenger RNA (mRNA) biomarkers were measured using quantitative polymerase chain reaction. Statistical analysis was performed using R software, version 2.9.

RESULTS

Three protein biomarkers (cathepsin D [CPD], α-enolase, and ß₂-microglobulin [ß₂m]) and 3 mRNA biomarkers (myeloid cell nuclear differentiation antigen [MNDA], guanylate binding protein 2 [GBP-2], and low-affinity IIIb receptor for the Fc fragment of IgG) were significantly elevated in patients with primary SS compared with both SLE patients and healthy controls. The combination of 3 protein biomarkers, CPD, α-enolase, and ß₂m, yielded a receiver operating characteristic (ROC) value of 0.99 in distinguishing primary SS from healthy controls. The combination of protein biomarkers ß₂m and 2 mRNA biomarkers, MNDA and GBP-2, reached an ROC of 0.95 in discriminating primary SS from SLE.

CONCLUSION

We have successfully verified a panel of protein and mRNA biomarkers that can discriminate primary SS from both SLE and healthy controls. If further validated in patients with primary SS and those with sicca symptoms but no autoimmune disease, these biomarkers may lead to a simple yet highly discriminatory clinical tool for diagnosis of primary SS.

RETRACTED: Blockade of TNF-α signaling suppresses the AREG-mediated IL-6 and IL-8 cytokines secretion induced by anti-Ro/SSA autoantibodies

The aim of this study was to analyze the Furin-TNF-α-converting enzyme (TACE)-amphiregulin (AREG)-IL-6/IL-8 secretion pathway in non-neoplastic human salivary gland epithelial cells (SGECs) stimulated with anti-Ro/SSA autoantibodies (Abs). We examined whether anti-Ro/SSA Abs-mediated TACE activation is responsible for AREG activation. As recent studies have demonstrated that AREG could induce proinflammatory cytokines secretion in epithelial cells, we discuss how TACE-mediated AREG shedding, caused by anti-Ro/SSA Abs treatment, could have a critical role in TNF-α-induced IL-6 and IL-8 secretion by SGEC. Furthermore, the effects of TNF-α blockade on AREG expression and TNF-α-AREG-mediated IL-6 and IL-8 secretion were evaluated. We have discovered that the upregulation of AREG occurs through TNF-α produced after anti-Ro/SSA Abs uptake via Fcγ receptors. Biological drug adalimumab and the gene silencing technique were used to study the AREG-IL-6/IL-8 secretion pathway, demonstrating that (i) adalimumab-mediated TNF-α blocking and TNF-α gene silencing provoke a significant decrease of proinflammatory cytokines production and AREG expression in anti-Ro/SSA Abs-treated SGEC; (ii) AREG gene silencing has a potent inhibitory effect on TNF-α-induced IL-6 and IL-8 secretion in SGEC treated with anti-Ro/SSA Abs; (iii) an inspection of the kinetics of cytokine production after exogeni TNF-α and AREG addition, and the use of cycloheximide in the presence of exogenous TNF-α as stimulant, clarified that TNF-α induces IL-6 and IL-8 secretion through AREG.Laboratory Investigation advance online publication, 20 September 2010; doi:10.1038/labinvest.2010.168.

Sphingosine-1-phosphate Signaling in Human Submandibular Cells

Sphingosine-1-phosphate (S1P) is a significant lipid messenger modulating many physiological responses. S1P plays a critical role in autoimmune disease and is suggested to be involved in Sjögren’s syndrome pathology. However, the mechanism of S1P signaling in salivary glands is unclear. Here we studied the effects of S1P on normal human submandibular gland cells. S1P increased levels of the intracellular Ca2+ concentration ([Ca2+]i), which was inhibited by pre-treatment with U73122 or 2-aminoethoxydiphenyl borate (2-APB). Pre-treated S1P did not inhibit subsequent carbachol-induced [Ca2+]i increase, which suggests that S1P and muscarinic signaling are independent of each other. S1P1, S1P2, and S1P3 receptors SphK1 and SphK2 were commonly expressed in human salivary gland cells. S1P, but not carbachol, induces the expression of interleukin-6 and Fas. Our results suggest that S1P triggers Ca2+ signaling and the apoptotic pathway in normal submandibular gland cells, which suggests in turn that S1P affects the progression of Sjögren’s syndrome.

Effectiveness of rituximab treatment in primary Sjögren's syndrome: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To study the efficacy and safety of B cell depletion with rituximab, a chimeric murine/human anti-CD20 monoclonal antibody, in patients with primary Sjögren's syndrome (SS) in a double-blind, randomized, placebo-controlled trial.

METHODS

Patients with active primary SS, as determined by the revised American-European Consensus Group criteria, and a rate of stimulated whole saliva secretion of > or =0.15 ml/minute were treated with either rituximab (1,000 mg) or placebo infusions on days 1 and 15. Patients were assigned randomly to a treatment group in a ratio of 2:1 (rituximab:placebo). Followup was conducted at 5, 12, 24, 36, and 48 weeks. The primary end point was the stimulated whole saliva flow rate, while secondary end points included functional, laboratory, and subjective variables.

RESULTS

Thirty patients with primary SS (29 female) were randomly allocated to a treatment group. The mean +/- SD age of the patients receiving rituximab was 43 +/- 11 years and the disease duration was 63 +/- 50 months, while patients in the placebo group were age 43 +/- 17 years and had a disease duration of 67 +/- 63 months. In the rituximab group, significant improvements, in terms of the mean change from baseline compared with that in the placebo group, were found for the primary end point of the stimulated whole saliva flow rate (P = 0.038 versus placebo) and also for various laboratory parameters (B cell and rheumatoid factor [RF] levels), subjective parameters (Multidimensional Fatigue Inventory [MFI] scores and visual analog scale [VAS] scores for sicca symptoms), and extraglandular manifestations. Moreover, in comparison with baseline values, rituximab treatment significantly improved the stimulated whole saliva flow rate (P = 0.004) and several other variables (e.g., B cell and RF levels, unstimulated whole saliva flow rate, lacrimal gland function on the lissamine green test, MFI scores, Short Form 36 health survey scores, and VAS scores for sicca symptoms). One patient in the rituximab group developed mild serum sickness-like disease.

CONCLUSION

These results indicate that rituximab is an effective and safe treatment strategy for patients with primary SS.

Health-related quality of life, employment and disability in patients with Sjogren's syndrome

OBJECTIVE

To compare health-related quality of life (HR-QOL), employment and disability of primary and secondary SS (pSS and sSS, respectively) patients with the general Dutch population.

METHODS

HR-QOL, employment and disability were assessed in SS patients regularly attending the University Medical Center Groningen (n = 235). HR-QOL, employment and disability were evaluated with the Short Form-36 questionnaire (SF-36) and an employment and disability questionnaire. Results were compared with Dutch population data (matched for sex and age). Demographical and clinical data associated with HR-QOL, employment and disability were assessed.

RESULTS

Response rate was 83%. SS patients scored lower on HR-QOL than the general Dutch population. sSS patients scored lower on physical functioning, bodily pain and general health than pSS patients. Predictors for reduced HR-QOL were fatigue, tendomyalgia, articular involvement, use of artificial saliva, use of anti-depressants, comorbidity, male sex and eligibility for disability compensation (DC). Employment was lower and DC rates were higher in SS patients compared with the Dutch population.

CONCLUSION

SS has a large impact on HR-QOL, employment and disability.

Systems biology analysis of Sjögren's syndrome and mucosa-associated lymphoid tissue lymphoma in parotid glands

OBJECTIVE

To identify key target genes and activated signaling pathways associated with the pathogenesis of Sjögren's syndrome (SS) by conducting a systems analysis of parotid glands manifesting primary SS or primary SS/mucosa-associated lymphoid tissue (MALT) lymphoma phenotypes.

METHODS

A systems biology approach was used to analyze parotid gland tissue samples obtained from patients with primary SS, patients with primary SS/MALT lymphoma, and subjects without primary SS (non-primary SS controls). The tissue samples were assessed concurrently by gene-expression microarray profiling and proteomics analysis, followed by weighted gene-coexpression network analysis.

RESULTS

Gene-coexpression modules related to primary SS and primary SS/MALT lymphoma were significantly enriched with genes known to be involved in the immune/defense response, apoptosis, cell signaling, gene regulation, and oxidative stress. Detailed functional pathway analyses indicated that primary SS-associated modules were enriched with genes involved in proteasome degradation, apoptosis, signal peptides of the class I major histocompatibility complex (MHC), complement activation, cell growth and death, and integrin-mediated cell adhesion, while primary SS/MALT lymphoma-associated modules were enriched with genes involved in translation, ribosome biogenesis and assembly, proteasome degradation, class I MHC signal peptides, the G13 signaling pathway, complement activation, and integrin-mediated cell adhesion. Combined analyses of gene expression and proteomics data implicated 6 highly connected "hub" genes for distinguishing primary SS from non-primary SS, and 8 hub genes for distinguishing primary SS/MALT lymphoma from primary SS.

CONCLUSION

Systems biology analyses of the parotid glands from patients with primary SS and those with primary SS/MALT lymphoma revealed pathways and molecular targets associated with disease pathogenesis. The identified gene modules/pathways provide further insights into the molecular mechanisms of primary SS and primary SS/MALT lymphoma. The identified disease-hub genes represent promising targets for therapeutic intervention, diagnosis, and prognosis.