Pro-inflammatory role of Anti-Ro/SSA autoantibodies through the activation of Furin–TACE–amphiregulin axis

Treg derived Amphiregulin protects from murine lupus nephritis via tissue reparative effects

Systemic lupus erythematosus (SLE) is a common autoimmune disease that affects multiple organ systems. Among the most severe manifestations of SLE is lupus nephritis (LN), which causes particularly high morbidity. Recently, we identified amphiregulin (AREG), an epidermal growth factor receptor ligand, as a key mediator of LN via downregulation of pathogenic CD4+ T-cell responses. In human LN, AREG is mainly produced by regulatory T cells (Tregs) and monocytes/macrophages (M/M). Since AREG´s functions have been shown to vary considerably depending on the source, we aimed to clarify the cell-type-specific roles of AREG using the pristane model of LN. Conditional knockout mice lacking Treg- but not M/M-derived AREG showed worse LN outcome at 12 and 15 months with increased glomerular cell proliferation, apoptosis and renal tissue fibrosis. Interestingly, immune responses were not relevantly affected by the lack of AREG from either leukocyte source, indicating a different mechanism. In this respect, in vitro studies demonstrated improved wound healing of murine mesangium and tubulus cells and enhanced regeneration and sprouting of human glomerular endothelial cells after incubation with recombinant AREG. These findings underscore the importance of Treg-derived AREG in tissue regeneration and protection from fibrosis in LN, highlighting AREG as a potential therapeutic target.

Clinical significance of amphiregulin in patients with chronic kidney disease

BACKGROUND

Amphiregulin (AREG) is a ligand of epidermal growth factor receptor (EGFR), which plays an important role in injury-induced kidney fibrosis. However, the clinical significance of serum soluble AREG in chronic kidney disease (CKD) is unclear. In this study, we elucidated the clinical significance of serum soluble AREG in CKD by analyzing the association of serum soluble AREG levels with renal function and other clinical parameters in patients with CKD.

METHODS

In total, 418 Japanese patients with CKD were enrolled, and serum samples were collected for the determination of soluble AREG and creatinine (Cr) levels, and other clinical parameters. Additionally, these parameters were evaluated after 2 and 3 years. Moreover, immunohistochemical assay was performed ate AREG expression in the kidney tissues of patients with CKD.

RESULTS

Soluble AREG levels were positively correlated with serum Cr (p < 0.0001). Notably, initial AREG levels were positively correlated with changes in renal function (ΔCr) after 2 (p < 0.0001) and 3 years (P = 0.048). Additionally, soluble AREG levels were significantly higher (p < 0.05) in patients with diabetic nephropathy or primary hypertension. Moreover, AREG was highly expressed in renal tubular cells in patients with advanced CKD, but only weakly expressed in patients with preserved renal function.

CONCLUSION

Serum soluble AREG levels were significantly correlated with renal function, and changes in renal function after 2 and 3 years, indicating that serum soluble AREG levels might serve as a biomarker of renal function and renal prognosis in CKD.

The Amphiregulin/EGFR axis protects from lupus nephritis via downregulation of pathogenic CD4+ T helper cell responses

Systemic lupus erythematosus (SLE) is a common autoimmune disorder with a complex and poorly understood immuno-pathogenesis. Lupus nephritis (LN) is a frequent and difficult to treat complication, which causes high morbidity and mortality. The multifunctional cytokine amphiregulin (AREG) has been implicated in SLE pathogenesis, but its function in LN currently remains unknown. We thus studied the model of pristane-induced LN and found increasing renal and systemic AREG expression during the course of disease. Importantly, renal injury was significantly aggravated in the absence of AREG, revealing a net anti-inflammatory role. Analyses of immune responses showed dual effects. On the one hand, AREG enhanced activation of pro-inflammatory myeloid cells, which however did not play a major role for the course of LN. More importantly, on the other hand, AREG strongly suppressed pathogenic cytokine production by T helper effector cells. This effect was more general in nature and could be reproduced in response to antigen immunization. Since AREG has been postulated to downregulate T cell responses via enhancing Treg suppressive capacity, we followed up on this aspect. Interestingly, however, in vitro studies revealed potential direct and Treg independent effects of AREG on T helper effector cells. In favor of this notion, we found significantly enhanced T cell responses and consecutive aggravation of LN, only if epidermal growth factor receptor (EGFR) signaling was abrogated in total T cells, but not if the EGFR was absent on Tregs alone. Finally, we also found enhanced AREG expression in plasma and renal biopsies of patients with LN, supporting the relevance of our findings for human disease. In summary, our data identify AREG as an anti-inflammatory mediator of LN via broad downregulation of pathogenic T cell immunity. These findings further highlight the AREG/EGFR axis as a potential therapeutic target.

Visually induced changes in cytokine production in the chick choroid

Postnatal ocular growth is regulated by a vision-dependent mechanism that acts to minimize refractive error through coordinated growth of the ocular tissues. Of great interest is the identification of the chemical signals that control visually guided ocular growth. Here, we provide evidence that the pro-inflammatory cytokine, interleukin-6 (IL-6), may play a pivotal role in the control of ocular growth using a chicken model of myopia. Microarray, real-time RT-qPCR, and ELISA analyses identified IL-6 upregulation in the choroids of chick eyes under two visual conditions that introduce myopic defocus and slow the rate of ocular elongation (recovery from induced myopia and compensation for positive lenses). Intraocular administration of atropine, an agent known to slow ocular elongation, also resulted in an increase in choroidal IL-6 gene expression. Nitric oxide appears to directly or indirectly upregulate choroidal IL-6 gene expression, as administration of the non-specific nitric oxide synthase inhibitor, L-NAME, inhibited choroidal IL-6 gene expression, and application of a nitric oxide donor stimulated IL-6 gene and protein expression in isolated chick choroids. Considering the pleiotropic nature of IL-6 and its involvement in many biological processes, these results suggest that IL-6 may mediate many aspects of the choroidal response in the control of ocular growth.

ADAM 17 and Epithelial-to-Mesenchymal Transition: The Evolving Story and Its Link to Fibrosis and Cancer

For decades, metalloproteinase 17 (ADAM17) has been the goal of wide investigation. Since its discovery as the tumour necrosis factor-α convertase, it has been studied as the main drug target, especially in the context of inflammatory conditions and tumour. In fact, evidence is mounting to support a key role of ADAM17 in the induction of the proliferation, migration and progression of tumour cells and the trigger of the pro-fibrotic process during chronic inflammatory conditions; this occurs, probably, through the activation of epithelial-to-mesenchymal transition (EMT). EMT is a central morphologic conversion that occurs in adults during wound healing, tumour progression and organ fibrosis. EMT is characterised by the disassembly of cell–cell contacts, remodelling of the actin cytoskeleton and separation of cells, and generates fibroblast-like cells that express mesenchymal markers and have migratory properties. This transition is characterised by loss of epithelial proteins such as E-cadherin and the acquisition of new mesenchymal markers, including vimentin and a-smooth muscle actin. The present review discusses the current understanding of molecular mechanisms involved in ADAM17-dependent EMT in order to individuate innovative therapeutic strategies using ADAM17-related pathways.

Relationships between increased circulating YKL-40, IL-6 and TNF-α levels and phenotypes and disease activity of primary Sjögren's syndrome

BACKGROUND

There is now no single score or marker useful for evaluating disease activity of primary Sjögren's syndrome (pSS). This study was designed to explore the associations of circulating YKL-40, interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) with systemic activity and phenotypes of pSS.

METHODS

This study included 58 pSS patients and 30 healthy controls (HC). The sera were measured by multiplex immunoassay for YKL-40, IL-6 and TNF-α concentrations. The disease activity of pSS patients was evaluated by European league against rheumatism (EULAR) SS disease activity index (ESSDAI). Local severity was assessed in accordance with the Tarpley score.

RESULTS

Serum YKL-40, IL-6 and TNF-α levels significantly elevated in pSS patients compared with those in HC (all P < 0.001). These cytokines correlated with ESSDAI, ESR, CRP, and IgG (all P < 0.05). Serum YKL-40 level correlated markedly with age (r = 0.405, P = 0.002), neutrophil count (r = 0.399, P = 0.002) and neutrophil-to-lymphocyte ratio (NLR) (r = 0.401, P = 0.002), while IL-6 did weakly with NLR (r = 0.296, P = 0.024) and C3 (r = 0.288, 0.036). Serum levels of all three cytokines were substantially lower in patients with eye/mouth dryness vs. those without (all P < 0.05). Additionally, patients with pulmonary, renal involvement or anemia had remarkably higher concentrations of YKL-40 (all P < 0.05), while those with leukocytopenia had lower levels (P = 0.01). Fever or anemia patients showed higher serum concentrations of IL-6 (both P < 0.05), while serum levels of TNF-α were much higher in patients with presence of ANA, anti-SSA or anti-SSB antibodies (All P < 0.05). Serum IL-6 level correlated strongly with YKL-40 (r = 0.452, P < 0.001) and TNF-α (r = 0.743, P < 0.001) in pSS patients. A significant correlation was also found between YKL-40 and TNF-α (r = 0.308, P = 0.022) .

CONCLUSION

The circulating YKL-40, IL-6 and TNF-α levels increase in pSS, and all of them are significantly correlated with indicators (ESSDAI, ESR, CRP, and IgG) for systemic inflammation of pSS. Each cytokine is separately associated with specific pSS phenotype.

IL-6 Contributes to the TGF-β1-Mediated Epithelial to Mesenchymal Transition in Human Salivary Gland Epithelial Cells

To determine the role of IL-6 in bringing about the EMT, in SGEC obtained from healthy subjects. Human salivary gland (SGs) epithelial cells (SGEC) from primary Sjögren's syndrome (pSS) are able to synthesize interleukin (IL)-6, which is a critical mediator of the SGs modifications in response to chronic inflammation. Recently, a hypothetical link between epithelial-mesenchymal transition (EMT)-dependent salivary gland fibrosis and chronic inflammatory conditions has been suggested for pSS; the present study was conducted to evaluate this link. Primary cultures of human SGEC from salivary mucoceles were stimulated with increasing concentrations of IL-6 for 24-72 h. Microscopy, RT-PCR, Real-time PCR, immunoblotting and flow cytometry were used to detect morphological changes, mRNA and protein expression of the EMT markers E-Cadherin, Vimentin and Collagen type I following IL-6 stimulation. The data collected demonstrate that IL-6 can induce SGEC to undergo a morphological and phenotypical transition to a mesenchymal phenotype, in a dose-dependent manner. Decreased mRNA levels of E-Cadherin accompanied by higher mRNA levels of Vimentin and Collagen type I were observed in the IL-6-treated cells compared to control cells (all p < 0.05). This was confirmed at the protein level, demonstrating the decreased E-Cadherin expression, while Vimentin and Collagen type I expression was increased in IL-6-treated SGEC compared to controls (all p < 0.05). The results obtained corroborate the hypothesis that dysregulated cytokines IL-6 may contribute to the EMT-dependent fibrosis, offering a more complete understanding of the role of the EMT during SGs fibrosis in pSS.

Understanding the Complexity of Sjögren's Syndrome: Remarkable Progress in Elucidating NF-κB Mechanisms

Sjögren’s syndrome (SS) is a systemic autoimmune inflammatory disease with a poorly defined aetiology, which targets exocrine glands (particularly salivary and lachrymal glands), affecting the secretory function. Patients suffering from SS exhibit persistent xerostomia and keratoconjunctivitis sicca. It is now widely acknowledged that a chronic grade of inflammation plays a central role in the initiation, progression, and development of SS. Consistent with its key role in organizing inflammatory responses, numerous recent studies have shown involvement of the transcription factor nuclear factor κ (kappa)-light-chain-enhancer of activated B cells (NF-κB) in the development of this disease. Therefore, chronic inflammation is considered as a critical factor in the disease aetiology, offering hope for the development of new drugs for treatment. The purpose of this review is to describe the current knowledge about the NF-κB-mediated molecular events implicated in the pathogenesis of SS.

Increased FURIN expression in rheumatoid arthritis patients and its anti-inflammatory effect

Background

FURIN belongs to the proprotein convertase family that processes proproteins and is involved in many diseases. However, the role of FURIN in rheumatoid arthritis (RA) remains unknown. In this study, we investigated the association between circulating FURIN and disease activity in patients with RA and the effect of FURIN in THP‐1‐derived macrophages.

Methods

A total of 108 RA patients and 39 healthy controls participants were included in this study. RA patients were divided into four disease activity groups determined by the Disease Activity Score of 28 joints (DAS28). FURIN expression in peripheral blood mononuclear cells (PBMCs) and serum was detected by using quantitative real‐time polymerase chain reaction (qRT‐PCR) and enzyme‐linked immunosorbent assay (ELISA), respectively. Western blotting and qRT‐PCR were used to detect cytokines level after interfering FURIN expressed in THP‐1‐derived macrophages.

Results

Both FURIN mRNA and protein levels were significantly higher in RA patients than in healthy controls participants (P < .001). No significant difference in FURIN expression was observed among the four RA groups (P > .05). Spearman correlation revealed that FURIN positively correlated with transforming growth factor‐β1(TGF‐β1), rheumatoid factor (RF), and anti‐cyclic citrullinated peptide (anti‐CCP). Moreover, the inhibition of FURIN in THP‐1‐derived macrophages promoted the caspase‐1 and IL‐1β expression (P < .05).

Conclusion

FURIN levels were significantly increased in the peripheral blood of RA patients and were not associated with disease activity. The inhibition of FURIN in THP‐1‐derived macrophages with elevated IL‐1β levels shows that FURIN may have an anti‐inflammatory effect.

Injection of CD40 DNA vaccine ameliorates the autoimmune pathology of non-obese diabetic mice with Sjögren's syndrome

BACKGROUND

Overexpression of CD40 has been reported in patients with primary Sjögren's syndrome (pSS). The increased CD40 expression promote autoimmune response and enhance inflammation in pSS. The aim of this study is to block CD40-CD154 interaction with CD40 DNA vaccine to slow the disease progression of SS in non-obese diabetic (NOD) mice.

METHODS

Female NOD mice were treated with CD40 DNA vaccine, empty vector and normal saline. The salivary flow rate was measured, whereas lymphocytes infiltration in the salivary glands was assessed by histopathology. Expression of CD40 and B220 in salivary were examined by immunohistochemistry. Splenic lymphocyte phenotypes were analyzed by flow cytometry. CD40, IL-1β, TNF-α and IL-6 levels in the salivary glands were detected by PCR. Serum anti-CD40 antibody was measured by ELISA. Serum anti-nuclear antibody (ANA) was monitored by immunofluorescence.

RESULTS

NOD mice treated with CD40 DNA vaccine showed higher levels of anti-CD40 antibody compared with the controls. The expression of CD40 in the salivary glands of NOD mice in CD40 DNA vaccine group was decreased. The infiltration of lymphocytes was reduced in the salivary glands and saliva secretion was increased in the treatment group. The expression level of TNF-α and IL-6 in salivary glands were declined. The splenic dendritic cell and plasma cell populations were reduced and the level of ANA was decreased in NOD mice with CD40 DNA vaccine treatment.

CONCLUSIONS

CD40 DNA vaccine inhibits the immune response and reduce inflammation in epithelial tissues SS in non-obese diabetic (NOD) mice, suggesting that CD40 DNA vaccine could be a new therapeutic approach in treatment of pSS.

Amphiregulin Aggravates Glomerulonephritis via Recruitment and Activation of Myeloid Cells

BACKGROUND

Recent studies have identified the EGF receptor (EGFR) ligand amphiregulin (AREG) as an important mediator of inflammatory diseases. Both pro- and anti-inflammatory functions have been described, but the role of AREG in GN remains unknown.

METHODS

The nephrotoxic nephritis model of GN was studied in AREG^-/- mice after bone marrow transplantation, and in mice with myeloid cell-specific EGFR deficiency. Therapeutic utility of AREG neutralization was assessed. Furthermore, AREG's effects on renal cells and monocytes/macrophages (M/M) were analyzed. Finally, we evaluated AREG expression in human renal biopsies.

RESULTS

Renal AREG mRNA was strongly upregulated in murine GN. Renal resident cells were the most functionally relevant source of AREG. Importantly, the observation that knockout mice showed significant amelioration of disease indicates that AREG is pathogenic in GN. AREG enhanced myeloid cell responses via inducing chemokine and colony stimulating factor 2 (CSF2) expression in kidney resident cells. Furthermore, AREG directly skewed M/M to a proinflammatory M1 phenotype and protected them from apoptosis. Consequently, anti-AREG antibody treatment dose-dependently ameliorated GN. Notably, selective abrogation of EGFR signaling in myeloid cells was sufficient to protect against nephritis. Finally, strong upregulation of AREG expression was also detected in kidneys of patients with two forms of crescentic GN.

CONCLUSIONS

AREG is a proinflammatory mediator of GN via (1) enhancing renal pathogenic myeloid cell infiltration and (2) direct effects on M/M polarization, proliferation, and cytokine secretion. The AREG/EGFR axis is a potential therapeutic target for acute GN.

Amphiregulin inhibits TNF-α-induced alveolar epithelial cell death through EGFR signaling pathway

BACKGROUND

We previously observed that amphiregulin (Areg), a ligand of epithelial growth factor receptor (EGFR), was highly expressed in lipopolysaccharide (LPS)-induced acute lung injury (ALI) lung tissues mainly by the classically activated (M1) alveolar macrophages (AMs). Areg also plays a protective role in LPS-induced injury in lung tissues and alveolar epithelial cells (AECs). However, whether Areg is co-expressed with tumor necrosis factor (TNF)-α in ALI lung tissues, and can directly inhibit TNF-α-induced AEC injury remains unclear.

METHODS

We first detected the kinetic expressions of Areg and TNF-α in LPS-stimulated lung tissues and M1 AMs and then identified the role of exogenous recombinant Areg (rmAreg) in the injured lung tissues. The effect of Areg on TNF-α-induced apoptosis in MLE-12 cells, a kind of AECs, was examined by terminal deoxynucleotidyl transferase dUTP nick end labeling staining. The activation of the EGFR-AKT pathway and caspase-3, -8, and -9 were detected by Western blotting. The EGFR knockdown by small interfering RNA was used to assess the role of EGFR in Areg functions.

RESULTS

Areg production occurred in close parallel with TNF-α expression in M1 AMs and ALI lung tissues, and rmAreg attenuated LPS-induced ALI in mice. TNF-α stimulation induced significant apoptosis in MLE-12 cells, but this apoptosis was inhibited under rmAreg treatment. Moreover, rmAreg enhanced the activation of EGFR and AKT, and reduced the expressions of cleaved caspase-3, -8, and -9 in ALI lung tissues and TNF-α-challenged MLE-12 cells. However, the EGFR knockdown significantly inhibited the Areg-induced improvement in apoptosis, enhancement of EGFR and AKT activation, and reduction of cleaved caspase-3, -8, and -9 expressions.

CONCLUSIONS

Areg and TNF-α were synchronously produced by ALI lung tissues and M1 AMs, and Areg directly inhibited the TNF-induced apoptosis and transduction of caspase death signals in AECs via the EGFR pathway.

Interleukin-17 and -22 synergy linking inflammation and EMT-dependent fibrosis in Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is a chronic inflammatory, autoimmune and systemic disorder commonly associated with dry eyes and a dry mouth. Recently, the hypothetical link between epithelial-mesenchymal transition (EMT)-dependent salivary gland (SG) fibrosis and chronic inflammatory conditions has been suggested. In this study, we present data demonstrating a negative correlation of the epithelial marker E-cadherin expression and a positive correlation of mesenchymal vimentin and collagen type I expression with increasing degrees of tissue inflammation in pSS SG specimens. In addition, as it is not clear whether dysregulated cytokines in pSS, interleukin (IL)-17 and IL-22 may also contribute to the EMT-dependent fibrosis process, the effect of IL-17 and IL-22 treatment on EMT-dependent SG fibrosis was evaluated in primary human salivary gland epithelial cells (SGEC) isolated from healthy subjects. Here we present data demonstrating that IL-17 and IL-22 can induce SGEC to undergo a morphological and phenotypical transition to a mesenchymal phenotype. In support of this, vimentin and collagen type I were up-regulated while a decreased expression of E-cadherin occurs after interleukin treatment, and co-operation between IL-17 and Il-22 was required to induce the EMT.

Proconvertase Furin Is Downregulated in Postural Orthostatic Tachycardia Syndrome

Background: Postural Orthostatic Tachycardia Syndrome (POTS) is a cardiovascular autonomic disorder characterized by orthostatic intolerance and high prevalence among young women. The etiology of POTS is uncertain, though autoimmunity and inflammation may play an important role. We aimed to identify novel inflammatory biomarkers associated with POTS.

Methods and Results: In the Syncope Study of Unselected Population in Malmö (SYSTEMA) cohort, we identified 396 patients (age range, 15–50 years) with either POTS (n = 113) or normal haemodynamic response during passive head-up-tilt test (n = 283). Blood samples were analyzed using antibody-based Proximity Extension Assay technique simultaneously measuring 57 inflammatory protein biomarkers. The discovery algorithm was a sequential two-step process of biomarker signature identification by supervised, multivariate, principal component analysis and verification by univariate ANOVA with Bonferroni correction. POTS patients were younger (26 vs. 31 years; p < 0.001) and there was no significant difference in sex distribution (74% vs. 67% females, p = 0.24). PCA and Bonferroni-adjusted ANOVA identified proconvertase furin as the most robust biomarker signature for POTS. Plasma level of proconvertase furin was lower (6.38 vs. 6.58 of normalized protein expression units (NPX); p < 0.001 in POTS, compared with the reference group. Proconvertase furin met Bonferroni-adjusted significance criteria in both uni- and multivariable regression analyses.

Conclusion: Patients with POTS have lower plasma level of proconvertase furin compared with individuals with normal postural hemodynamic response. This finding suggests the presence of a specific autoimmune trait with disruption of immune peripheral tolerance in this hitherto unexplained condition. Further studies are needed for external validation of our results.

[A case of neuromyelitis optica spectrum disorder (NMOSD) with Sjögren's syndrome manifested only brain involvement by preceding parotitis]

A 33 year-old woman presented with intentional incontinence, motor aphasia, supranuclear gaze palsy, and spasticity after parotitis. Brain magnetic resonance images (MRI) showed abnormal signaling in long corticospinal tract involving internal capsules and cerebral peduncles, middle cerebellar peduncle, and frontal subcortical white matter lesions. She had a long history of dry eye and mouth. Immunoserological study showed that she was positive for anti-SS-A, aquaporin 4 (AQP4), and AQP5 antibodies. She clinically showed not only Sjögren's syndrome but also neuromyelitis optica spectrum disorder (NMOSD) without optic neuritis or myelitis. She responded to steroid followed by plasma exchange dramatically. Thereafter, the relapse of brain lesion was once detected while tapering of steroid, but her symptoms have been stable for several years after administration of immunosuppressant. This case suggested that salivary gland inflammation might be associated with the pathogenesis of NMOSD.

Rituximab-mediated Raf kinase inhibitor protein induction modulates NF-κB in Sjögren syndrome

Primary Sjögren syndrome (pSS) is an autoimmune disorder characterized by an epithelial injury surrounded by dense lymphocytic infiltrates. The conditions for the long-term maintenance of human salivary gland epithelial cells from pSS patients and a co-culture system with pSS lymphocytes were used to assess the effect of Rituximab (RTX) on the inflammatory condition and progression in pSS. Quantitative real-time PCR, genes and protein array analysis, Western blot, flow cytometry, small interfering RNA transfection and nuclear factor-κB (NF-κB) DNA binding assays were used as methods. Supporting the benefits of RTX, this study demonstrates that RTX decreases NF-κB activity and interrupts the NF-κB signalling pathway through the up-regulation of the Raf-1 kinase inhibitor protein (RKIP). Over-expression of RKIP down-regulates interleukins, their receptors and the expression of genes encodes proteins that attracted lymphocytes. Silencing of the RKIP gene leads to significantly increased expression and release of pro-inflammatory mediators supporting that RKIP expression could be involved in the suppression of NF-κB activation in pSS salivary gland epithelial cells.

ADAM17 at the interface between inflammation and autoimmunity

The discovery of the disintegrin and metalloproteinase 17 (ADAM17), originally identified as tumor necrosis factor-a converting enzyme (TACE) for its ability as sheddase of TNF-α inspired scientists to attempt to elucidate the molecular mechanisms underlying ADAM17 implication in diseased conditions. In recent years, it has become evident that this protease can modify many non matrix substrates, such as cytokines (e.g. TNF-α), cytokine receptors (e.g. IL-6R and TNF-R), ligands of ErbB (e.g. TGF-α and amphiregulin) and adhesion proteins (e.g. Lselectin and ICAM-1). Several recent studies have described experimental model system to better understand the role of specific signaling molecules, the interplay of different signals and tissue interactions in regulating ADAM17-dependent cleavage of most relevant substrates in inflammatory diseases. The central question is whether ADAM17 can influence the outcome of inflammation and if so, how it performs this regulation in autoimmunity, since inflammatory autoimmune diseases are often characterized by deregulated metalloproteinase activities. This review will explore the latest research on the influence of ADAM17 on the progression of inflammatory processes linked to autoimmunity and its role as modulator of inflammation.

Neovascularization is prominent in the chronic inflammatory lesions of Sjögren's syndrome

Angiogenesis is a common finding in chronic inflammatory diseases; however, its role in Sjögren's syndrome (SS) remains to be elucidated. Previous SS studies have demonstrated an increase in VEGF-A/VEGFR-2 system expression in minor salivary gland (MSG) biopsies from patients with SS, but differences in the new blood vessel formation between the different grades of disease severity have not been reported. Therefore, experiments were performed to demonstrate angiogenesis during different phases of primary SS (pSS) and to define the relationship between the microvessel density (MVD), macrophage infiltration and histiocyte distribution in SS MSG inflammatory lesions. In this series of experiments, immunohistochemistry was used to examine angiogenesis in serial sections of pSS MSG. Patients with pSS were classified accordingly with the grade of inflammatory lesions as I = low-grade (low focus score of 1 or 2), II = intermediate-grade (focus score of 3–6) and III = extensive inflammation in the MSG (high focus score of 12). Histological examination demonstrated that the MVD increased with the severity of the inflammatory lesions, and in addition, we found an increased infiltration of inflammatory and pro-angiogenic cells.These findings reveal that angiogenesis is intimately involved in the progression of pSS, may be central to the propagation of the chronic immune response observed in pSS and could represent a novel potential biomarker of pSS disease activity.

Amphiregulin

Amphiregulin (AREG) is a ligand of the epidermal growth factor receptor (EGFR), a widely expressed transmembrane tyrosine kinase. AREG is synthesized as a membrane-anchored precursor protein that can engage in juxtacrine signaling on adjacent cells. Alternatively, after proteolytic processing by cell membrane proteases, mainly TACE/ADAM17, AREG is secreted and behaves as an autocrine or paracrine factor. AREG gene expression and release is induced by a plethora of stimuli including inflammatory lipids, cytokines, hormones, growth factors and xenobiotics. Through EGFR binding AREG activates major intracellular signaling cascades governing cell survival, proliferation and motility. Physiologically, AREG plays an important role in the development and maturation of mammary glands, bone tissue and oocytes. Chronic elevation of AREG expression is increasingly associated with different pathological conditions, mostly of inflammatory and/or neoplastic nature. Here we review the essential aspects of AREG structure, function and regulation, discuss the basis for its differential role within the EGFR family of ligands, and identify emerging aspects in AREG research with translational potential.

The autoimmune side of heart and lung diseases

The elevated cardiovascular morbidity in rheumatoid arthritis, systemic lupus erythematosus, and the antiphospholipid syndrome is well known, as well as the pulmonary involvement observed in these conditions and to a major extent in systemic sclerosis. These manifestations constitute a major challenge for clinicians involved in patient management. Moreover, several issues regarding the link between autoimmune rheumatic diseases and cardio pulmonary morbidity remain largely enigmatic. The mechanistic role of certain autoantibodies frequently observed in association with heart and lung diseases or the pathogenetic link between chronic inflammation and the pathways leading to atherosclerosis or pulmonary vascular changes are yet to be elucidated. As such, these questions as well as treatment strategies are of common interest to rheumatologists, immunologist, pulmonologists, and cardiologists and thus call for an interdisciplinary approach. This paradigm has been well established for rare conditions such as the Churg-Strauss syndrome. Nowadays, it seems that this approach should be expanded to encompass more common conditions such as coronary heart disease, pulmonary arterial hypertension or dilated cardiomyopathy. The present issue of Clinical Reviews in Allergy and Immunology addresses the new knowledge and concepts of autoimmune-related cardiopulmonary diseases. The issue derives from the 2010 International Autoimmunity Meeting held in Ljubljana, Slovenia and is thus timely and dedicated to the latest developments in this new multidisciplinary field.

Altered IκBα expression promotes NF-κB activation in monocytes from primary Sjögren's syndrome patients

AIMS

To study the importance of IκBα in NF-κB signal transduction, we analysed the IκBα expression in monocytes from Sjögren's syndrome (SS) patients versus healthy controls.

METHODS

Monocytes were obtained from the peripheral blood of 30 SS patients and 23 healthy subjects. IκBα expression was studied by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), real-time PCR, immunoblotting, flow cytometry and enzyme linked immunosorbent assay (ELISA).

RESULTS

Analysis of the gene and protein expression profiles of SS monocytes revealed a down-regulation of IκBα, and in all the Sjögren's syndrome cases examined, serum IκBα levels were significantly decreased in comparison with controls.

CONCLUSIONS

Our findings clearly demonstrate changes in the levels of IκBα in SS monocytes, suggesting that the attenuated expression of IκBα could contribute to the deregulation of NF-κB pathways in the SS pathogenesis. Decreased expression of IκBα may specifically amplify cytokines production and inflammatory response linked to Sjögren's syndrome.

Novel aspects of Sjögren's syndrome in 2012

Sjögren's syndrome (SS) is a systemic progressive autoimmune disease characterized by a complex pathogenesis requiring a predisposing genetic background and involving immune cell activation and autoantibody production. The immune response is directed to the exocrine glands, causing the typical 'sicca syndrome', but major organ involvement is also often seen. The etiology of the disease is unknown. Infections could play a pivotal role: compared to normal subjects, patients with SS displayed higher titers of anti-Epstein-Barr virus (EBV) early antigens, but lower titers of other infectious agent antibodies such as rubella and cytomegalovirus (CMV) suggest that some infections may have a protective role against the development of autoimmune disease. Recent findings seem to show that low vitamin D levels in patients with SS could be associated with severe complications such as lymphoma and peripheral neuropathy. This could open new insights into the disease etiology. The current treatments for SS range from symptomatic therapies to systemic immunosuppressive drugs, especially B cell-targeted drugs in cases of organ involvement. Vitamin D supplementation may be an additional tool for optimization of SS treatment.

Salivary gland expression level of IκBα regulatory protein in Sjögren's syndrome

Diagnosis and therapeutic strategies in Sjögren's syndrome (SS) might greatly benefit of the present multidisciplinary approach to studying the molecular pathogenesis of the disease. A deregulated inflammatory response has been described in the SS. The research in the last years sheds light on the importance of the NF-κB pathway regulating the pro-inflammatory cytokine production and leukocyte recruitment. These are important contributors to the inflammatory response during the development of SS. In this study we examine the expression of the NF-κB inhibitory protein termed IκBα in salivary glands epithelial cells (SGEC) comparing it with SGEC from healthy controls, to test the hypothesis that an altered expression of IκBα occurs in SGEC from SS biopsies. Real-Time PCR, western blot and immunohistochemistry demonstrated that the expression level of IκBα was significantly lower in SS with respect to healthy controls leading to an increased NF-κB activity. Our results suggest that the analysis of IκBα expression at salivary gland epithelial cell level could be a potential new hallmark of SS progression and sustain a rationale to more deeply investigate the therapeutic potential of specific NF-κB inhibitors in SS.

Emerging avenues linking inflammation, angiogenesis and Sjögren's syndrome

Sjögren's syndrome (SS) is an autoimmune disease characterized by an inflammatory mononuclear infiltration and the destruction of epithelial cells of the lachrymal and salivary glands. The aetiology is unknown. The expression "autoimmune epithelitis" has been proposed as an alternative to SS, in view of the emerging central role of the epithelial cells in the disease pathogenesis. At the biomolecular level, the epithelial cells play an important role in triggering the autoimmune condition via antigen presentation, apoptosis, and chemokine and cytokines release. Inflammation and angiogenesis are frequently coupled in the pathological conditions associated to autoimmune diseases, and an angiogenic imbalance contributes to the pathogenesis of a number of inflammatory disorders. This work reviews the current knowledge of the molecular and cellular mechanisms underlying the pathogenesis of the inflammatory reactions that characterize SS. The literature and our data on the role of angiogenesis in the pathophysiology of the disease are discussed.

A potential role of the GRO-α/CXCR2 system in Sjögren's syndrome: regulatory effects of pro-inflammatory cytokines

Chemokines, small pro-inflammatory cytokines, are involved in migration of inflammatory cells in inflamed tissues and recent studies established their role in angiogenesis, hematopoiesis, cancer and autoimmune conditions. Growth related oncogene-alpha (GRO-α), a member of the CXC chemokine family, and its receptor CXCR2 are involved in the inflammatory processes. Since there is no previous report that supports a possible role of GRO-α/CXCR2 receptor complex during inflammation and neovascularization existing in the autoimmune disease Sjögren's syndrome (SS), in this study, we examined CXCR2 and its ligand GRO-α expression in SS tissues. Immunohistochemistry revealed that GRO-α and its receptor CXCR2 were expressed at high levels in diseased tissues compared to healthy controls. In addition, human salivary gland epithelial cells (SGEC) cultures were submitted to a pro-inflammatory microenvironment using cytokines IL-6 and TNF-α in order to demonstrate that CXCR2 may change its initial expression pattern to another under inflammatory condition. The data show an increased expression of CXCR2 depending on the inflammatory cytokine used in culture in a time-dependent manner. Furthermore, silencing of the pro-angiogenic chemokine GRO-α is proportionally correlated with decreased expression of CXCR2 in pro-inflammatory cytokine-stimulated SGEC indicating the GRO-α/CXCR2 complex as a novel therapeutic target for the chronic inflammatory disease Sjögren's syndrome.

Occurrence of salivary gland tumours in two patients treated with biological agents

We report two cases of salivary gland tumors arising in two psoriatic patients treated with an anti- TNF-alpha agent. A clear causal relationship could not be established, but the exceptional onset of a bilateral Warthin&#x0027;s tumor in one of these patients should be emphasized.

Sjögren's syndrome pathological neovascularization is regulated by VEGF-A-stimulated TACE-dependent crosstalk between VEGFR2 and NF-κB

We explore the involvement of tumor necrosis factor α (TNF-α)-converting enzyme (TACE) in vascular endothelial growth factor (VEGF) and its receptor 2 (VEGFR2) (VEGF-A/VEGFR2)-mediated angiogenesis in Sjögren's syndrome (SS), one of the most common autoimmune rheumatic diseases. To test the hypothesis that SS autoantibodies (Abs) regulate VEGF-A/VEGFR2 expression by a TACE-dependent nuclear factor-κB (NF-κB) activation pathway, their effects on the expression and activation of the VEGF-A/TACE/VEGFR2/NF-κB pathway were determined in human salivary gland epithelial cells (SGEC). An enhanced angiogenesis in SS salivary gland biopsies was observed, associated with an increased VEGF-A expression and activation of VEGF-A/VEGFR2 signaling. Human cytokine array analysis of the pro-inflammatory and pro-angiogenic protein response in SGEC treated with SS Abs revealed an overexpression of multiple pro-angiogenic factors. TACE RNA knockdown, the use of anti-VEGF-A monoclonal antibody and the inhibition of NF-κB activity significantly abrogated the release of pro-angiogenic factors, demonstrating that VEGF-A/TACE/VEGFR2/NF-κB axis dysfunction may be contributory to pathogenesis and exacerbation of this autoimmune condition.

Sjögren's syndrome autoantibodies provoke changes in gene expression profiles of inflammatory cytokines triggering a pathway involving TACE/NF-κB

We explore the association of the inflammatory gene expression profile observed in the chronic inflammatory autoimmune disorder Sjögren's syndrome (SS) with changes in TNF-α converting enzyme (TACE), tumor necrosis factor (TNF)-α and nuclear factor (NF)-κB levels showing that pathways that include TNF-α signaling converge on NF-κB contributing to exacerbate the diseases. The treatment of human salivary gland epithelial cells (SGECs) with SS anti-Ro/SSA autoantibodies (Abs) result in a progressive increase in NF-κB-DNA binding, that includes a marked enhancement in NF-κB subunit p65 protein-DNA binding. A human cytokine multi-analyte array demonstrated that the NF-κB proinflammatory target genes, increased by anti-Ro/SSA Abs treatment, includes CXC chemokines (CXCL1, CXCL6 and CXCL9), CC chemokines (CCL2, CCL13 and CCL20), interleukins (IL-1α, IL-1β, IL-1F8, IL-6, IL-8, IL-9, IL-13, IL-17 and IL-22) and their receptors (IL-1RN, IL-10Rα, IL-13Rα, CCR1, CCR2, CCR3, CCR4 and CXCR1). Blockade of TACE through the use of the specific inhibitor TAPI-1 regulates proinflammatory cytokines production in SGEC treated with anti-Ro/SSA Abs inhibiting NF-κB nuclear translocation and activation. To further investigate the role of NF-κB on anti-Ro/SSA Abs-determined proinflammatory gene expression, we used the inhibitory protein IκB-α dominant negative super-repressor as inhibitor of NF-κB-DNA binding, demonstrating that transfection with dominant-negative IκB-α in anti-Ro/SSA-treated SGEC determined a marked reduction of proinflammatory cytokines gene expression. Although further studies are needed to clarify the mechanisms underlying SS, our results demonstrate that SS Abs exert their pathogenic effects via triggering the TACE/TNF-α/NF-κB axis.

Neuropilin-1 is upregulated in Sjögren's syndrome and contributes to pathological neovascularization

Neuropilin-1 (NRP1) is a transmembrane co-receptor for members of the vascular endothelial growth factor family. Recent studies revealed an important role of NRP1 in angiogenesis and progression of many diseases. The role of NRP1 in the development of Sjögren's syndrome (SS), one of the most common rheumatic diseases, has not yet been investigated. Molecular studies and protein expression techniques were performed to elucidate the gene and protein expression profile of NRP1 in human salivary gland epithelial cells (SGEC) from primary SS. We used human microarrays and transient transfection with a mutant form of the negative inhibitory κBα proteins (IκBαDN) to investigate whether selective inhibition of nuclear Factor-κB (NF-κB) improves NRP1-mediated pro-angiogenic factors release from SS SGEC. The selective NRP1 function inhibition with an antibody to human NRP1, was employed to evaluate the therapeutic potential of targeting NRP1. We demonstrate that NRP1 is expressed in SGEC of both human healthy biopsies and in SS samples, and increased NRP1 expression in SS SGEC is significantly associated with pro-angiogenic factors release. Neutralizing anti-NRP1 antibody decreased pro-angiogenic factor production from SS SGEC and blocking NF-κB activation could be a way to inhibit NRP1-mediated angiogenesis in Sjögren's syndrome.

Primary biliary cirrhosis and Sjögren's syndrome: autoimmune epithelitis

Primary biliary cirrhosis (PBC) has been often coined a model autoimmune disease based on the homogeneity amongst patients, the frequency and similarity of antimitochondrial antibodies, including the highly directed immune response to pyruvate dehydrogenase (PDC-E2). A significant number of patients with PBC suffer from sicca and amongst these, there are patients who also have classic Sjögren's syndrome. Indeed, both PBC and Sjögren's syndrome are characterized by inflammation of target epithelial elements. Both diseases can be considered on the basis of a number of other related clinical aspects, including proposed unique apoptotic features of the target tissue, the role of secretory IgA, and the frequency with which both diseases overlap with each other. Indeed, PBC may be considered a Sjögren's syndrome of the liver, whereas Sjögren's syndrome can be equally discussed as PBC of the salivary glands. Dissection of the genetic predispositions for both diseases and especially the molecular basis of effector mechanisms, will become critical elements in developing new therapies.

Decreased salivary sulphotransferase activity correlated with inflammation and autoimmunity parameters in Sjogren's syndrome patients

OBJECTIVES

To determine the expression and enzymatic activities of sulphotransferases involved in mucin hyposulphation in labial salivary glands (LSGs) from SS patients and to correlate sulphotransferase activity with clinical parameters such as secretion, inflammation and serology.

METHODS

LSG from 31 SS patients and 31 control subjects were studied. Relative mRNA and protein levels of Gal3-O-sulphotransferases (Gal3STs) and β1,3-galactosyltransferase-5 (β3GalT5) were determined by quantitative RT-PCR and western blotting, respectively. Enzymatic activities were quantified using radioactively labelled donor substrates and specific acceptor substrates. Products were purified by chromatography. Spearman's correlation analysis was used to compare data.

RESULTS

The levels of Gal3ST activity were significantly decreased in SS patients, without changes in mRNA and protein levels, while the enzymatic activities of glycosyltransferases involved in mucin glycosylation were similar in both groups. An inverse correlation was observed between Gal3ST activity and glandular function measured by scintigraphy, but not with unstimulated salivary flow. Gal3ST activity was inversely correlated with focus score, TNF-α levels and presence of the autoantibodies Ro/SS-A and La/SS-B.

CONCLUSION

The decrease in sulphotransferase activity provides an explanation for mucin hyposulphation observed in the LSGs from SS patients. The decrease in Gal3STs activity was not a consequence of reduced gene expression, but probably due to alterations in the enzyme activity regulation. Interestingly, the levels of sulphotransferase activity detected correlated well with secretory function, inflammation and serology. Finally, we postulate that pro-inflammatory cytokines induced by autoantibodies, such as Ro/SS-A and La/SS-B in SS patients, may modulate Gal3ST activity, thereby altering mucin quality and leading to mouth dryness.

The complexity of Sjögren's syndrome: novel aspects on pathogenesis

In Sjögren's syndrome, like in most other autoimmune diseases, the enigma leading to a pathogenic attack against self has not yet been solved. By definition, the disease must be mediated by specific immune reactions against endogenous tissues to qualify as an autoimmune disease. In Sjögren's syndrome the autoimmune response is directed against the exocrine glands, which, as histopathological hallmark of the disease, display persistent and progressive focal mononuclear cell infiltrates. Clinically, the disease in most patients is manifested by two severe symptoms: dryness of the mouth (xerostomia) and the eyes (keratoconjunctivitis sicca). A number of systemic features have also been described and the presence of autoantibodies against the ubiquitously expressed ribonucleoprotein particles Ro (Sjögren's-syndrome-related antigen A - SSA) and La (SSB) further underline the systemic nature of Sjögren's syndrome. The original explanatory concept for the pathogenesis of Sjögren's syndrome proposed a specific, self-perpetuating, immune mediated loss of acinar and ductal cells as the principal cause of salivary gland hypofunction. Although straightforward and plausible, the hypothesis, however, falls short of accommodating several Sjögren's syndrome-related phenomena and experimental findings. Consequently, researchers considered immune-mediated salivary gland dysfunction prior to glandular destruction and atrophy as potential molecular mechanisms underlying the symptoms of dryness in Sjögren's syndrome. Accordingly, apoptosis, fibrosis and atrophy of the salivary glands would represent consequences of salivary gland hypofunction. The emergence of advanced bio-analytical platforms further enabled the identification of potential biomarkers with the intent to improve Sjögren's syndrome diagnosis, promote the development of prognostic tools for Sjögren's syndrome and the long-term goal to identify possible processes for therapeutic treatment interventions. In addition, such approaches allowed us to glimpse at the apparent complexity of Sjögren's syndrome.

Autoimmunity in 2010

There is now growing evidence that autoimmunity is the common trait connecting multiple clinical phenotypes albeit differences in tissue specificity, pathogenetic mechanisms, and therapeutic approaches cannot be overlooked. Over the past years we witnessed a constant growth of the number of publications related to autoimmune diseases in peer-reviewed journals of the immunology area. Original data referred to factors from common injury pathways (i.e. T helper 17 cells, serum autoantibodies, or vitamin D) and specific diseases such as multiple sclerosis, systemic lupus erythematosus, and rheumatoid arthritis. As an example, the issue of a latitudinal gradient in the prevalence and incidence rates has been proposed for all autoimmune diseases and was recently coined as geoepidemiology to suggest new environmental triggers for tolerance breakdown. The present article is aimed at reviewing the articles that were published over the past year in the major autoimmunity and immunology journals.

A failure of TNFAIP3 negative regulation maintains sustained NF-κB activation in Sjögren's syndrome

Sjögren's syndrome (SS) is characterized by the features of systemic autoimmunity and exocrine gland dysfunction and inflammation. Deregulated cytokine production is known to contribute to the etiology of SS but the underlying molecular mechanism is still remains to be unclear. TNF-α-induced protein 3 or TNFAIP3 is involved in the negative feedback regulation of nuclear factor-κB (NF-κB) signaling in response to specific pro-inflammatory stimuli in different cell types. To define the contribution of TNFAIP3 to SS, the levels of TNFAIP3 expression in human salivary gland epithelial cells (SGEC) derived from active primary SS patients were analyzed. Histological analysis was performed on paraffin-embedded human Sjögren's samples and healthy tissues. In separate experiments, immunofluorescence staining, western blot analysis and quantitative real-time PCR for TNFAIP3 was conducted in SGEC from SS and healthy subjects. Our findings clearly demonstrate changes in levels of the protein and gene expression between healthy controls and SS patients, depicting a very weak positivity for TNFAIP3 in SS samples. TNFAIP3 was found down-regulated in SGECs derived from SS patients in comparison with controls, and the cells with down-regulated TNFAIP3 expression exhibited enhanced NF-κB activities. In addition, to investigate the role of TNFAIP3 in the activation of NF-κB, we depleted TNFAIP3 expression by siRNA in healthy SGEC after treatment with or without TNF-α. Intriguingly, the silencing of TNFAIP3 by its siRNA in healthy SGEC increased NF-κB activation that could explain the deregulated cytokines production observed in SS.