Patients with Primary Sjögren's Syndrome Have Alterations in Absolute Quantities of Specific Peripheral Leucocyte Populations

Possible role for IL-40 and IL-40-producing cells in the lymphocytic infiltrated salivary glands of patients with primary Sjögren's syndrome

OBJECTIVES

Aim of this study was to investigate the expression of interleukin (IL)-40, a new cytokine associated with B cells homoeostasis and immune response, in primary Sjögren syndrome (pSS) and in pSS-associated lymphomas.

METHODS

29 patients with pSS and 24 controls were enrolled. Minor salivary gland (MSG) biopsies from patients, controls and parotid gland biopsies from pSS-associated lymphoma were obtained. Quantitative gene expression analysis by TaqMan real-time PCR and immunohistochemistry for IL-40 were performed on MSG. MSG cellular sources of IL-40 were determined by flow-cytometry and immunofluorescence. Serum concentration of IL-40 was assessed by ELISA and cellular sources of IL-40 were determined by flow-cytometry. An in vitro assay with recombinant IL-40 (rIL-40) was performed to detect the effect on cytokine production from peripheral blood mononuclear cells (PBMCs).

RESULTS

IL-40 was significantly increased in the lymphocytic infiltrated MSG of patients with pSS and correlated with focus score and with IL-4 and transforming growth factor-β expression. In addition, IL-40 was increased in the serum of pSS and its levels correlated with the EULAR Sjögren's Syndrome Disease Activity Index score. B cells from patients were shown to be the major source of IL-40 at both tissue and peripheral level. PBMCs from patients, exposed to rIL-40 in vitro, released proinflammatory cytokines, specifically interferon-γ from B cells and T-CD8⁺ and tumour necrosis factor-α and IL-17 from both T-CD4⁺ and T-CD8⁺. IL-40 expression in parotid glands of pSS-associated lymphomas was also increased. Moreover, IL-40-driven NETosis was evidenced in neutrophils obtained from pSS.

CONCLUSION

Our results suggest that IL-40 may play a role in pSS pathogenesis and pSS-associated lymphomas.

Exploiting the role of T cells in the pathogenesis of Sjögren's syndrome for therapeutic treatment

Sjögrens syndrome (SS) is caused by autoantibodies that attack proprioceptive salivary and lacrimal gland tissues. Damage to the glands leads to dry mouth and eyes and affects multiple systems and organs. In severe cases, SS is life-threatening because it can lead to interstitial lung disease, renal insufficiency, and lymphoma. Histological examination of the labial minor salivary glands of patients with SS reveals focal lymphocyte aggregation of T and B cells. More studies have been conducted on the role of B cells in the pathogenesis of SS, whereas the role of T cells has only recently attracted the attention of researchers. This review focusses on the role of various populations of T cells in the pathogenesis of SS and the progress made in research to therapeutically targeting T cells for the treatment of patients with SS.

Aberrant signaling of immune cells in Sjögren’s syndrome patient subgroups upon interferon stimulation

Background

Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease, characterized by mononuclear cell infiltrates in the salivary and lacrimal glands, leading to glandular atrophy and dryness. Patient heterogeneity and lack of knowledge regarding its pathogenesis makes pSS a difficult disease to manage.

Methods

An exploratory analysis using mass cytometry was conducted of MAPK/ERK and JAK/STAT signaling pathways in peripheral blood mononuclear cells (PBMC) from 16 female medication free pSS patients (8 anti-Sjögren’s syndrome-related antigen A negative/SSA- and 8 SSA+) and 8 female age-matched healthy donors after stimulation with interferons (IFNs).

Results

We found significant differences in the frequencies of memory B cells, CD8+ T central and effector memory cells and terminally differentiated CD4+ T cells among the healthy donors and patient subgroups. In addition, we observed an upregulation of HLA-DR and CD38 in many cell subsets in the patients. Upon IFNα2b stimulation, slightly increased signaling through pSTAT1 Y701 was observed in most cell types in pSS patients compared to controls, while phosphorylation of STAT3 Y705 and STAT5 Y694 were slightly reduced. IFNγ stimulation resulted in significantly increased pSTAT1 Y701 induction in conventional dendritic cells (cDCs) and classical and non-classical monocytes in the patients. Most of the observed differences were more prominent in the SSA+ subgroup, indicating greater disease severity in them.

Conclusions

Augmented activation status of certain cell types along with potentiated pSTAT1 Y701 signaling and reduced pSTAT3 Y705 and pSTAT5 Y694 induction may predispose pSS patients, especially the SSA+ subgroup, to upregulated expression of IFN-induced genes and production of autoantibodies. These patients may benefit from therapies targeting these pathways.

Anti-Ro/SSA and/or anti-La/SSB antibodies are associated with adverse IVF and pregnancy outcomes

Anti-Ro/SSA and/or anti-La/SSB antibodies (anti-SSA/SSB) were reported to increase the risk of recurrent pregnancy loss. However, the effects of anti-SSA/SSB antibodies on in-vitro fertilization (IVF) and pregnancy outcomes were still unclear. The purpose of the study was to determine whether anti-SSA/SSB antibodies were detrimental to IVF and pregnancy outcomes. This study included 55 anti-SSA/SSB antibodies-positive women and 61 anti-SSA/SSB antibodies-negative control women receiving gonadotropin-releasing hormone (GnRH) agonist long protocol (n = 30 and 39, respectively) or GnRH antagonist protocol (n = 25 and 22, respectively) for in-vitro fertilization and embryo transfer (IVF-ET). The impact of anti-SSA/SSB antibodies on immune-related indicators, fertilization, embryo development and pregnancy outcomes were analyzed. With either GnRH agonist or antagonist protocol, women with anti-SSA/SSB had higher levels of peripheral blood cytokines, including TNF-α and IL-17A, lower levels of peripheral blood Th and NK cells, and poor IVF outcomes, including lower number of retrieved oocytes and embryos, lower M II oocytes rate, blastocyst formation rate, and perfect and available embryo rates. Moreover, clinical pregnancy rate, implantation rate, take-home baby rate, and birth weight were significantly lower in the study group as compared with those of the control group. In conclusion, women with anti-SSA/SSB are associated with adverse IVF and pregnancy outcomes. Screening for these antibodies and proper counselling of couples undergoing IVF-ET should be considered. Underlying immunopathology associated with SSA/SSB antibodies and reproduction should be explored further.

Regulatory B Cells Involvement in Autoimmune Phenomena Occurring in Pediatric Graves' Disease Patients

Graves’s disease is the most common type of autoimmune hyperthyroidism. Numerous studies indicate different factors contributing to the onset of the disease. Despite years of research, the exact pathomechanism of Graves’ disease still remains unresolved, especially in the context of immune response. B cells can play a dual role in autoimmune reactions, on the one hand, as a source of autoantibody mainly targeted in the thyroid hormone receptor (TSHR) and, on the other, by suppressing the activity of proinflammatory cells (as regulatory B cells). To date, data on the contribution of Bregs in Graves’ pathomechanism, especially in children, are scarce. Here, we investigated the frequencies of Bregs before and during a methimazole therapy approach. We reported higher Foxp3+ and IL-10+ Breg levels with CD38- phenotype and reduced numbers of CD38 + Foxp3 + IL-10+ in pediatric Graves’ patients. In addition, selected Breg subsets were found to correlate with TSH and TRAb levels significantly. Noteworthy, certain subpopulations of Bregs were demonstrated as prognostic factors for methimazole therapy outcome. Our data demonstrate the crucial role of Bregs and their potential use as a biomarker in Graves’ disease management.

A new molecular classification to drive precision treatment strategies in primary Sjögren's syndrome

There is currently no approved treatment for primary Sjögren's syndrome, a disease that primarily affects adult women. The difficulty in developing effective therapies is -in part- because of the heterogeneity in the clinical manifestation and pathophysiology of the disease. Finding common molecular signatures among patient subgroups could improve our understanding of disease etiology, and facilitate the development of targeted therapeutics. Here, we report, in a cross-sectional cohort, a molecular classification scheme for Sjögren's syndrome patients based on the multi-omic profiling of whole blood samples from a European cohort of over 300 patients, and a similar number of age and gender-matched healthy volunteers. Using transcriptomic, genomic, epigenetic, cytokine expression and flow cytometry data, combined with clinical parameters, we identify four groups of patients with distinct patterns of immune dysregulation. The biomarkers we identify can be used by machine learning classifiers to sort future patients into subgroups, allowing the re-evaluation of response to treatments in clinical trials.

NK Cells in Autoimmune Diseases: Protective or Pathogenic?

Autoimmune diseases generally result from the loss of self-tolerance (i.e., failure of the immune system to distinguish self from non-self), and are characterized by autoantibody production and hyperactivation of T cells, which leads to damage of specific or multiple organs. Thus, autoimmune diseases can be classified as organ-specific or systemic. Genetic and environmental factors contribute to the development of autoimmunity. Recent studies have demonstrated the contribution of innate immunity to the onset of autoimmune diseases. Natural killer (NK) cells, which are key components of the innate immune system, have been implicated in the development of multiple autoimmune diseases such as systemic lupus erythematosus, type I diabetes mellitus, and autoimmune liver disease. However, NK cells have both protective and pathogenic roles in autoimmunity depending on the NK cell subset, microenvironment, and disease type or stage. In this work, we review the current knowledge of the varied roles of NK cell subsets in systemic and organic-specific autoimmune diseases and their clinical potential as therapeutic targets.

Utility of lymphocyte phenotype profile to differentiate primary Sjögren syndrome from Sicca syndrome

BACKGROUND

blood B cell profile has been proposed to have diagnostic utility in primary Sjögren syndrome (pSS), but the potential utility of advanced lymphocyte profiling to differentiate between pSS and Sicca syndrome has not been fully investigated.

METHODS

distribution of peripheral lymphocyte subpopulations was analysed by flow cytometry in 68 patients with pSS, 26 patients with Sicca syndrome and 23 healthy controls. The ability to discriminate between pSS and Sicca syndrome was analysed using the area under the curve (AUC) of the receiver operating characteristic curve of the different lymphocyte subsets.

RESULTS

the ratio between naïve/memory B cell proportions showed an AUC of 0.742 to differentiate pSS and Sicca syndrome, with a sensitivity of 76.6% and a specificity of 72% for a cut-off value of 3.4. The ratio of non-switched memory B cells to activated CD4+ T cells percentage (BNSM/CD4ACT) presented the highest AUC (0.840) with a sensitivity of 83.3% and specificity of 81.7% for a cut-off value < 4.1. To differentiate seronegative pSS patients from Sicca patients the BNSM/CD4ACT ratio exhibited an AUC of 0.742 (sensitivity 75%, specificity 66.7%, cut-off value < 4.4), and the number of naïve CD4 T cells had an AUC of 0.821 (sensitivity 76.9%, specificity 88.9%, cut-off value < 312/mm3).

CONCLUSION

patients with pSS show a profound imbalance in the distribution of circulating T and B lymphocytes subsets. The ratio BNSM/CD4ACT is useful to discriminate between pSS and Sicca syndrome.

Natural Killer Cells: Potential Biomarkers and Therapeutic Target in Autoimmune Diseases?

Autoimmune diseases recognize a multifactorial pathogenesis, although the exact mechanism responsible for their onset remains to be fully elucidated. Over the past few years, the role of natural killer (NK) cells in shaping immune responses has been highlighted even though their involvement is profoundly linked to the subpopulation involved and to the site where such interaction takes place. The aberrant number and functionality of NK cells have been reported in several different autoimmune disorders. In the present review, we report the most recent findings regarding the involvement of NK cells in both systemic and organ-specific autoimmune diseases, including type 1 diabetes (T1D), primary biliary cholangitis (PBC), systemic sclerosis, systemic lupus erythematosus (SLE), primary Sjögren syndrome, rheumatoid arthritis, and multiple sclerosis. In T1D, innate inflammation induces NK cell activation, disrupting the Treg function. In addition, certain genetic variants identified as risk factors for T1D influenced the activation of NK cells promoting their cytotoxic activity. The role of NK cells has also been demonstrated in the pathogenesis of PBC mediating direct or indirect biliary epithelial cell destruction. NK cell frequency and number were enhanced in both the peripheral blood and the liver of patients and associated with increased NK cell cytotoxic activity and perforin expression levels. NK cells were also involved in the perpetuation of disease through autoreactive CD4 T cell activation in the presence of antigen-presenting cells. In systemic sclerosis (SSc), in addition to phenotypic abnormalities, patients presented a reduction in CD56^hi NK-cells. Moreover, NK cells presented a deficient killing activity. The influence of the activating and inhibitory killer cell immunoglobulin-like receptors (KIRs) has been investigated in SSc and SLE susceptibility. Furthermore, autoantibodies to KIRs have been identified in different systemic autoimmune conditions. Because of its role in modulating the immune-mediated pathology, NK subpopulation could represent a potential marker for disease activity and target for therapeutic intervention.

The Increased Ratio of Blood CD56bright NK to CD56dim NK Is a Distinguishing Feature of Primary Sjögren's Syndrome

Objective

The aim of this study was to characterize the subsets of circulating CD56⁺ NK cells in pSS patients and their potential value in the diagnosis and/or prediction of prognosis in patients with pSS.

Methods

We included 52 pSS patients fulfilling the 2002 AECG criteria or 2012 ACR criteria and 20 age- and gender-matched healthy volunteers. The frequency and absolute number of NK cells and CD56 NK cell subsets in peripheral blood samples were detected by flow cytometry. Other laboratory parameters such as the IgG level and complement protein levels were extracted from the clinical system.

Results

Both the frequency and the absolute number of peripheral blood NK cells were reduced in pSS patients compared to healthy controls. The proportion of CD56^bright NK cell subset was increased, and the proportion of CD56^dim NK cell subset was decreased among NK cells, resulting in the ratio of CD56^bright NK to CD56^dim NK which was significantly elevated in pSS patients. ROC analysis indicated that the AUC of CD56^bright NK/CD56^dim NK ratio was 0.838, and the best diagnostic cut-off point was 0.0487 for pSS patients. Furthermore, this CD56^bright NK/CD56^dim NK ratio was positively correlated with the IgG level and negatively correlated with the complement protein C3 and C4 levels. More importantly, the CD56^bright/CD56^dim NK ratio was either slightly increased or not changed in other autoimmune diseases such as SLE and IgG4-related disease.

Conclusion

Our findings suggest that the ratio of blood CD56^bright NK to CD56^dim NK might have a diagnostic value relatively specific for pSS.

Invariant NKT Cells and Rheumatic Disease: Focus on Primary Sjogren Syndrome

Primary Sjogren syndrome (pSS) is a complex autoimmune disease mainly affecting salivary and lacrimal glands. Several factors contribute to pSS pathogenesis; in particular, innate immunity seems to play a key role in disease etiology. Invariant natural killer (NK) T cells (iNKT) are a T-cell subset able to recognize glycolipid antigens. Their function remains unclear, but studies have pointed out their ability to modulate the immune system through the promotion of specific cytokine milieu. In this review, we discussed the possible role of iNKT in pSS development, as well as their implications as future markers of disease activity.

Single Cell Based Phosphorylation Profiling Identifies Alterations in Toll-Like Receptor 7 and 9 Signaling in Patients With Primary Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is associated with polymorphisms and mRNA expression profiles that are indicative of an exaggerated innate and type I IFN immune response. Excessive activation potential of signaling pathways may play a role in this profile, but the intracellular signaling profile of the disease is not well characterized. To gain insights into potentially dysfunctional intracellular signaling profiles of pSS patients we conducted an exploratory analysis of MAPK/ERK and JAK/STAT signaling networks in peripheral blood mononuclear cells (PBMC) from 25 female pSS patients and 25 female age-matched healthy donors using phospho-specific flow cytometry. We analyzed unstimulated samples, as well as samples during a 4 h time period following activation of Toll-like receptor (TLR) 7 and 9. Expression levels of MxA, IFI44, OAS1, GBP1, and GBP2 in PBMC were analyzed by real-time PCR. Cytokine levels in plasma were determined using a 25-plex Luminex-assay. Principal component analysis (PCA) showed that basal phosphorylation profiles could be used to differentiate pSS patients from healthy donor samples by stronger intracellular signaling pathway activation in NK and T cells relative to B cells. Stimulation of PBMC with TLR7 and -9 ligands showed significant differences in the phosphorylation profiles between samples from pSS patients and healthy donors. Including clinical parameters such as extraglandular manifestations (EGM), we observed stronger responses of NF-κB and STAT3 S727 in B cells from EGM-negative patients compared to EGM-positive patients and healthy controls. Plasma cytokine levels were correlated to the basal phosphorylation levels in these patients. In addition, 70% of the patients had a positive IFN score. These patients differed from the IFN score negative patients regarding their phosphorylation profiles and their plasma cytokine levels. In conclusion, we here report increased signaling potentials in peripheral B cells of pSS patients in response to TLR7 and -9 stimulation through STAT3 S727 and NF-κB that correlate with a type I IFN signature. Induction of these pathways could contribute to the generation of a type I IFN signature in pSS. Patients displaying elevated potentiation of STAT3 S727 and NF-κB signaling could therefore benefit from therapies targeting these pathways.

Innate immunity and interferons in the pathogenesis of Sjögren's syndrome

Primary SS (pSS) is a rheumatic disease characterized by an immune-mediated exocrinopathy, resulting in severe dryness of eyes and mouth. Systemic symptoms include fatigue and joint pain and a subset of patients develop more severe disease with multi-organ involvement. Accumulating evidence points to involvement of innate immunity and aberrant activity of the type I IFN system in both the initiation and propagation of this disease. Analysis of the activity of IFN-inducible genes has evidenced that more than half of pSS patients present with a so-called 'type I IFN signature'. In this review, we examine activation of the IFN system in pSS patients and how this may drive autoimmunity through various immune cells. We further discuss the clinical value of assessing IFN activity as a biomarker in pSS patients and review novel therapies targeting IFN signalling and their potential use in pSS.

RAB11FIP5 Expression and Altered Natural Killer Cell Function Are Associated with Induction of HIV Broadly Neutralizing Antibody Responses

HIV-1 broadly neutralizing antibodies (bnAbs) are difficult to induce with vaccines but are generated in ∼50% of HIV-1-infected individuals. Understanding the molecular mechanisms of host control of bnAb induction is critical to vaccine design. Here, we performed a transcriptome analysis of blood mononuclear cells from 47 HIV-1-infected individuals who made bnAbs and 46 HIV-1-infected individuals who did not and identified in bnAb individuals upregulation of RAB11FIP5, encoding a Rab effector protein associated with recycling endosomes. Natural killer (NK) cells had the highest differential expression of RAB11FIP5, which was associated with greater dysregulation of NK cell subsets in bnAb subjects. NK cells from bnAb individuals had a more adaptive/dysfunctional phenotype and exhibited impaired degranulation and cytokine production that correlated with RAB11FIP5 transcript levels. Moreover, RAB11FIP5 overexpression modulated the function of NK cells. These data suggest that NK cells and Rab11 recycling endosomal transport are involved in regulation of HIV-1 bnAb development.

•

Elevated RAB11FIP5 expression is associated with HIV-1 bnAb induction

•

NK cells show the highest differential RAB11FIP5 expression

•

NK cell subsets are more dysregulated in individuals developing bnAbs

•

Rab11Fip5 regulates NK cell function

B cells in the pathogenesis of primary Sjögren syndrome

Primary Sjögren syndrome (pSS) is a prototypical autoimmune disease. The involvement of B cells in the pathogenesis of pSS has long been suspected on the basis of clinical observations that include the presence of serum autoantibodies, hypergammaglobulinaemia, increased levels of free light chains and increased risk of B cell lymphoma. Moreover, the composition of the B cell subset is altered in pSS. In this Review, we discuss the mechanisms that support the increased activation of B cells in pSS, including genetic and epigenetic factors and environmental triggers that promote B cell activation via the innate immune system. B cell activating factor (BAFF, also known as TNF ligand superfamily member 13B) is at the crossroads of this process. An important role also exists for the target tissue (exocrine glands, namely the salivary and lachrymal glands), which promotes local B cell activation. This continuous stimulation of B cells is the main driver of lymphomatous escape. Identification of the multiple steps that support B cell activation has led to the development of promising targeted therapies that will hopefully lead to the development of an efficient therapeutic strategy for pSS.