Metastasis-inducing S100A4 protein is associated with the disease activity of rheumatoid arthritis

S-100 Proteins: Basics and Applications as Biomarkers in Animals with Special Focus on Calgranulins (S100A8, A9, and A12)

S100 proteins are a group of calcium-binding proteins which received this name because of their solubility in a 100% saturated solution of ammonium sulphate. They have a similar molecular mass of 10-12 KDa and share 25-65% similarity in their amino acid sequence. They are expressed in many tissues, and to date 25 different types of S100 proteins have been identified. This review aims to provide updated information about S100 proteins and their use as biomarkers in veterinary science, with special emphasis on the family of calgranulins that includes S100A8 (calgranulin A; myeloid-related protein 8, MRP8), S100A9 (calgranulin B; MRP14), and S100A12 (calgranulin C). The proteins SA100A8 and S100A9 can be linked, forming a heterodimer which is known as calprotectin. Calgranulins are related to the activation of inflammation and the immune system and increase in gastrointestinal diseases, inflammation and sepsis, immunomediated diseases, and obesity and endocrine disorders in different animal species. This review reflects the current knowledge about calgranulins in veterinary science, which should increase in the future to clarify their role in different diseases and potential as biomarkers and therapeutic targets, as well as the practical use of their measurement in non-invasive samples such as saliva or feces.

Secreted S100A4 causes asthmatic airway epithelial barrier dysfunction induced by house dust mite extracts via activating VEGFA/VEGFR2 pathway

The airway epithelial barrier dysfunction plays a crucial role in pathogenesis of asthma and causes the amplification of downstream inflammatory signal pathway. S100 calcium binding protein A4 (S100A4), which promotes metastasis, have recently been discovered as an effective inflammatory factor and elevated in bronchoalveolar lavage fluid in asthmatic mice. Vascular endothelial growth factor-A (VEGFA), is considered as vital regulator in vascular physiological activities. Here, we explored the probably function of S100A4 and VEGFA in asthma model dealt with house dust mite (HDM) extracts. Our results showed that secreted S100A4 caused epithelial barrier dysfunction, airway inflammation and the release of T-helper 2 cytokines through the activation of VEGFA/VEGFR2 signaling pathway, which could be partial reversed by S100A4 polyclonal antibody, niclosamide and S100A4 knockdown, representing a potential therapeutic target for airway epithelial barrier dysfunction in asthma.

Contribution of S100A4-expressing fibroblasts to anti-SSA/Ro-associated atrioventricular nodal calcification and soluble S100A4 as a biomarker of clinical severity

Background

Fibrosis and dystrophic calcification disrupting conduction tissue architecture are histopathological lesions characterizing cardiac manifestations of neonatal lupus (cardiac-NL) associated with maternal anti-SSA/Ro antibodies.

Objectives

Increased appreciation of heterogeneity in fibroblasts encourages re-examination of existing models with the consideration of multiple fibroblast subtypes (and their unique functional differences) in mind. This study addressed fibroblast heterogeneity by examining expression of α-Smooth Muscle Actin (myofibroblasts) and of S100 Calcium-Binding Protein A4 (S100A4).

Methods

Using a previously established model of rheumatic scarring/fibrosis in vitro, supported by the evaluation of cord blood from cardiac-NL neonates and their healthy (anti-SSA/Ro-exposed) counterparts, and autopsy tissue from fetuses dying with cardiac-NL, the current study was initiated to more clearly define and distinguish the S100A4-positive fibroblast in the fetal cardiac environment.

Results

S100A4 immunostaining was observed in 4 cardiac-NL hearts with positional identity in the conduction system at regions of dystrophic calcification but not fibrotic zones, the latter containing only myofibroblasts. In vitro, fibroblasts cultured with supernatants of macrophages transfected with hY3 (noncoding ssRNA) differentiated into myofibroblasts or S100A4+ fibroblasts. Myofibroblasts expressed collagen while S100A4+ fibroblasts expressed pro-angiogenic cytokines and proteases that degrade collagen. Cord blood levels of S100A4 in anti-SSA/Ro-exposed neonates tracked disease severity and, in discordant twins, distinguished affected from unaffected.

Conclusions

These findings position the S100A4+ fibroblast alongside the canonical myofibroblast in the pathogenesis of cardiac-NL. Neonatal S100A4 levels support a novel biomarker of poor prognosis.

S100 Proteins in Fatty Liver Disease and Hepatocellular Carcinoma

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent and slow progressing hepatic pathology characterized by different stages of increasing severity which can ultimately give rise to the development of hepatocellular carcinoma (HCC). Besides drastic lifestyle changes, few drugs are effective to some extent alleviate NAFLD and HCC remains a poorly curable cancer. Among the deregulated molecular mechanisms promoting NAFLD and HCC, several members of the S100 proteins family appear to play an important role in the development of hepatic steatosis, non-alcoholic steatohepatitis (NASH) and HCC. Specific members of this Ca²⁺-binding protein family are indeed significantly overexpressed in either parenchymal or non-parenchymal liver cells, where they exert pleiotropic pathological functions driving NAFLD/NASH to severe stages and/or cancer development. The aberrant activity of S100 specific isoforms has also been reported to drive malignancy in liver cancers. Herein, we discuss the implication of several key members of this family, e.g., S100A4, S100A6, S100A8, S100A9 and S100A11, in NAFLD and HCC, with a particular focus on their intracellular versus extracellular functions in different hepatic cell types. Their clinical relevance as non-invasive diagnostic/prognostic biomarkers for the different stages of NAFLD and HCC, or their pharmacological targeting for therapeutic purpose, is further debated.

Role of the S100 protein family in rheumatoid arthritis

Rheumatoid arthritis is a chronic systemic autoimmune disease characterized by synovial hyperplasia, inflammatory cell infiltration, and proliferation of inflammatory tissue (angiogranuloma). The destruction of joints and surrounding tissues eventually causes joint deformities and dysfunction or even loss. The S100 protein family is one of the biggest subtribes in the calcium-binding protein family and has more than 20 members. The overexpression of most S100 proteins in rheumatoid arthritis is closely related to its pathogenesis. This paper reviews the relationship between S100 proteins and the occurrence and development of rheumatoid arthritis. It will provide insights into the development of new clinical diagnostic markers and therapeutic targets for rheumatoid arthritis.

Role of S100A4 in the Pathogenesis of Human Periapical Granulomas

BACKGROUND/AIM

S100A4 expression is associated with the pathology of chronic inflammatory diseases. In this study, we investigated the role of S100A4 and four inflammatory mediators (IL-1β, IκB, IL-10, and TNF-α) in human periapical granulomas (PGs).

MATERIALS AND METHODS

S100A4 expression in PGs obtained by apicoectomy was examined by immunohistochemistry. Further, the expression of S100A4 and four inflammatory mediators was compared between PGs and healthy gingival tissues (HGTs) using real-time PCR.

RESULTS

In the PGs, S100A4 was found to be expressed in endothelial cells and fibroblasts. Furthermore, real-time PCR revealed that the expression of S100A4 and IL-1β in PGs was significantly higher than that in HGTs. Although a correlation between the expression of S100A4 and IκB or IL-10 was not detected, a positive correlation between the expression of S100A4 and IL-1β or TNF-α was observed.

CONCLUSION

The expression of S100A4 correlates with the pathogenesis of PGs.

S100A11 (calgizzarin) is released via NETosis in rheumatoid arthritis (RA) and stimulates IL-6 and TNF secretion by neutrophils

S100A11 (calgizzarin), a member of S100 family, is associated with several autoimmune diseases, including rheumatoid arthritis (RA). Neutrophil extracellular traps (NETs) are implicated in the pathogenesis of RA and in the externalization of some S100 family members. Therefore, we aimed to determine the association between S100A11 and NETs in RA. For this purpose, the levels of S100A11 and NETosis markers were detected in the RA synovial fluid by immunoassays. The expression of S100A11 by neutrophils in the RA synovial tissue was assessed. Neutrophils isolated from peripheral blood were exposed to S100A11 or stimulated to release NETs. The levels of NETosis- and inflammation-associated proteins were analysed by immunoassays. NETs were visualized by immunofluorescence. We showed that S100A11 was expressed by the neutrophils in the RA synovial tissue. Moreover, S100A11 in the RA synovial fluid correlated with several NETosis markers. In vitro, S100A11 was abundantly released by neutrophils undergoing NETosis compared to untreated cells (p < 0.001). Extracellular S100A11 increased the secretion of IL-6 (p < 0.05) and TNF (p < 0.05) by neutrophils but did not induce NETosis. This study demonstrates, for the first time, that the release of S100A11 is dependent on NETosis and that extracellular S100A11 augments the inflammatory response by inducing pro-inflammatory cytokines in neutrophils.

Extracellular S100A4 as a key player in fibrotic diseases

Fibrosis is characterized by fibroblast activation, extracellular matrix (ECM) accumulation and infiltration of inflammatory cells that sometimes leads to irreversible organ dysfunction. Considerable evidence now indicates that inflammation plays a critical role in the initiation and progression of organ fibrosis. S100A4 protein, a ubiquitous member of the S100 family, has recently been discovered as a potential factor implicated in fibrotic diseases. S100A4 protein is released at inflammatory site and has a certain biological function to promote cell motility, invasion, ECM remodelling, autophagy and angiogenesis. In addition, extracellular S100A4 is also a potential causation of inflammatory processes and induces the release of cytokines and growth factors under different pathological conditions. Elevated S100A4 level in patients’ serum closely correlates with disease activity in several fibrotic diseases and serves as a useful biomarker for diagnosis and monitoring disease progression. Analyses of knockout mouse models have identified a functional role of extracellular S100A4 protein in fibrotic diseases, suggesting that suppressing its expression, release or function might be a promising therapeutic strategy. This review will focus on the role of extracellular S100A4 as a key regulator of pro‐inflammatory signalling pathways and its relative biological processes involved in the pathogenesis of fibrosis.

S100A4 is elevated in axial spondyloarthritis: a potential link to disease severity

Background

S100A4 is a member of calcium binding S100 protein family well known for its role in cancer progression and metastasis. Nevertheless, S100A4 also serves as a negative regulator of bone formation. Dickkopf-1 (DKK-1), marker of bone remodelling, is also implicated in the process of syndesmophyte formation in ankylosing spondylitis. The aim of our study was to evaluate plasma levels of S100A4 in patients with axial spondyloarthritis and to determine the potential association of S100A4 with disease severity, clinical manifestations and with bone changes in a cross-sectional study.

Methods

Fifty-eight patients with axial spondyloarthritis and 40 healthy controls were studied. Biological samples were analysed for S100A4 and Dickkopf-1. Disease activity was assessed according to the Bath Ankylosing Spondylitis Disease Activity Index. C-reactive protein (CRP) was used as a marker of inflammation. Radiographic damage was assessed using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS).

Results

The plasma levels of S100A4 were significantly higher in patients with axial spondyloarthritis compared to heathy controls (p < 0.0001). The levels of S100A4 were higher in early stages of the disease and lower in patients with the presence of syndesmophytes (p = 0.009). Furthermore, we found weak but significant inverse correlation of plasma S100A4 with the mSASSS (r = − 0.363, p = 0.030). Levels of S100A4 were negatively associated with disease duration (r = − 0.404, p = 0.002) and positively with Dickkopf-1 binding capacity (r = 0.312, p = 0.023).

Conclusions

This is the first study showing elevated circulating levels of S100A4 in patients with axial spondyloarthritis, particularly in early stages of the disease prior to spinal involvement, and its significantly lower levels in patients with syndesmophytes. The role of S100A4 in the pathogenesis of axial spondyloarthritis can be suggested.

Serum Amyloid A Proteins Induce Pathogenic Th17 Cells and Promote Inflammatory Disease

Lymphoid cells that produce interleukin (IL)-17 cytokines protect barrier tissues from pathogenic microbes but are also prominent effectors of inflammation and autoimmune disease. T helper 17 (Th17) cells, defined by RORγt-dependent production of IL-17A and IL-17F, exert homeostatic functions in the gut upon microbiota-directed differentiation from naive CD4⁺ T cells. In the non-pathogenic setting, their cytokine production is regulated by serum amyloid A proteins (SAA1 and SAA2) secreted by adjacent intestinal epithelial cells. However, Th17 cell behaviors vary markedly according to their environment. Here, we show that SAAs additionally direct a pathogenic pro-inflammatory Th17 cell differentiation program, acting directly on T cells in collaboration with STAT3-activating cytokines. Using loss- and gain-of-function mouse models, we show that SAA1, SAA2, and SAA3 have distinct systemic and local functions in promoting Th17-mediated inflammatory diseases. These studies suggest that T cell signaling pathways modulated by the SAAs may be attractive targets for anti-inflammatory therapies.

The Multifaceted S100A4 Protein in Cancer and Inflammation

The metastasis-promoting S100A4 protein, a member of the S100 family, has recently been discovered as a potent factor implicated in various inflammation-associated diseases. S100A4 is involved in a range of biological functions such as angiogenesis, cell differentiation, apoptosis, motility, and invasion. Moreover, S100A4 is also a potent trigger of inflammatory processes and induces the release of cytokines and growth factors under different pathological conditions.Indeed, the release of S100A4 upon stress and mainly its pro-inflammatory role emerges as the most decisive activity in disease development, such as rheumatoid arthritis (RA), systemic sclerosis (SSc) allergy, psoriasis, and cancer. In the scope of this review, we will focus on the role of S100A4 as a mediator of pro-inflammatory pathways and its associated biological processes involved in the pathogenesis of various human noncommunicable diseases (NCDs) including cancer.

S100 proteins as therapeutic targets

The human genome codes for 21 S100 protein family members, which exhibit cell- and tissue-specific expression patterns. Despite sharing a high degree of sequence and structural similarity, the S100 proteins bind a diverse range of protein targets and contribute to a broad array of intracellular and extracellular functions. Consequently, the S100 proteins regulate multiple cellular processes such as proliferation, migration and/or invasion, and differentiation, and play important roles in a variety of cancers, autoimmune diseases, and chronic inflammatory disorders. This review focuses on the development of S100 neutralizing antibodies and small molecule inhibitors and their potential therapeutic use in controlling disease progression and severity.

Role of metastasis-induced protein S100A4 in human non-tumor pathophysiologies

S100A4, an important member of the S100 family of proteins, is best known for its significant role in promoting cancer progression and metastasis. In addition to its expression in tumors, upregulation of S100A4 expression has been associated with various non-tumor pathophysiology processes. However, the mechanisms underlying the role of S100A4 remain unclear. Activated “host” cells (fibroblasts, immunocytes, vascular cells, among others) secrete S100A4 into the extracellular space in various non-tumor human disorders, where it executes its biological functions by interacting with intracellular target proteins. However, the exact molecular mechanisms underlying these interactions in different non-tumor pathophysiologies vary, and S100A4 is likely one of the cross-linking factors that acts as common intrinsic constituents of biological mechanisms. Numerous studies have indicated that the S100A4-mediated epithelial–mesenchymal transition plays a vital role in the occurrence and development of various non-tumor pathophysiologies. Epithelial–mesenchymal transition can be categorized into three general subtypes based on the phenotype and function of the output cells. S100A4 regulates tissue fibrosis associated with the type II epithelial–mesenchymal transition via various signaling pathways. Additionally, S100A4 stimulates fibroblasts to secrete fibronectin and collagen, thus forming the structural components of the extracellular matrix (ECM) and stimulating their deposition in tissues, contributing to the formation of a pro-inflammatory niche. Simultaneously, S100A4 enhances the motility of macrophages, neutrophils, and leukocytes and promotes the recruitment and chemotaxis of these inflammatory cells to regulate inflammation and immune functions. S100A4 also exerts a neuroprotective pro-survival effect on neurons by rescuing them from brain injury and participates in angiogenesis by interacting with other target molecules. In this review, we summarize the role of S100A4 in fibrosis, inflammation, immune response, neuroprotection, angiogenesis, and some common non-tumor diseases as well as its possible involvement in molecular pathways and potential clinical value.

The predictive value of serum S100A9 and response to etanercept is not confirmed in a large UK rheumatoid arthritis cohort

Objective

The aim was to correlate protein concentrations of S100A9 in pretreatment serum samples with response to the tumour-necrosis factor (TNF) inhibitor drugs etanercept in a large UK replication cohort.

Methods

Pretreatment serum samples from patients with RA (n = 236) about to commence treatment with etanercept had S100A9 serum concentration measured using an ELISA. Following the experimental procedure, S100A9 concentrations were analysed with respect to EULAR response.

Results

No evidence of association between S100A9 concentration and EULAR response to the TNF-inhibitor biologic drug etanercept was observed following multinomial logistic regression analysis (non-responder vs moderate responder, P = 0.957; and non-responder vs good responder, P = 0.316). Furthermore, no significant associations were observed when correlating pretreatment S100A9 concentrations with clinical parameters of disease activity (P > 0.05).

Conclusion

In the largest replication cohort conducted to date, no evidence for association was observed to support the use of S100A9 as a clinical biomarker predictive of response to the TNF-inhibitor biologic drug etanercept.

Calgizzarin (S100A11): a novel inflammatory mediator associated with disease activity of rheumatoid arthritis

Background

Calgizzarin (S100A11) is a member of the S100 protein family that acts in different tumors by regulating a number of biologic functions. Recent data suggest its association with low-grade inflammation in osteoarthritis (OA). The aim of our study is to compare S100A11 expression in the synovial tissues, synovial fluid and serum of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and to characterize the potential association between S100A11 and disease activity.

Methods

S100A11 protein expression was detected in synovial tissue from patients with RA (n = 6) and patients with OA (n = 6) by immunohistochemistry and immunofluorescence. Serum and synovial fluid S100A11 levels were measured by ELISA in patients with RA (n = 40) and patients with OA (n = 34). Disease activity scores in 28 joints based on C-reactive protein (DAS28-CRP) were used to assess disease activity. Cytokine content in peripheral blood mononuclear cells (PBMCs), synovial fibroblasts (SFs) and synovial fluid was analysed by ELISA, western blotting or cytometric bead array.

Results

S100A11 expression was significantly up-regulated in the synovial lining and sublining layers (p < 0.01) and vessels (p < 0.05) of patients with RA compared to patients with OA, and was associated with fibroblasts and T cells. S100A11 was significantly increased in synovial fluid (p < 0.0001) but not in serum (p = 0.158) from patients with RA compared to patients with OA when adjusted for age and sex. Synovial fluid S100A11 correlated with DAS28 (r = 0.350, p = 0.027), serum CRP (r = 0.463, p = 0.003), synovial fluid leukocyte count (r = 0.677, p < 0.001), anti-cyclic citrullinated peptide antibodies (anti-CCP) (r = 0.424, p = 0.006) and IL-6 (r = 0.578, p = 0.002) and IL-8 (r = 0.740, p < 0.001) in synovial fluid from patients with RA. PBMCs and SFs isolated from patients with RA synthesized and spontaneously secreted higher levels of S100A11 in comparison with PBMCs and SFs from patients with OA (p = 0.011 and 0.03, respectively). S100A11 stimulated the production of the pro-inflammatory cytokine IL-6 by PBMCs (p < 0.05) and SFs (p < 0.01).

Conclusions

Our data provide the first evidence of S100A11 up-regulation and its association with inflammation and disease activity in patients with RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1288-y) contains supplementary material, which is available to authorized users.

Targeting STOX1 in the therapy of preeclampsia

INTRODUCTION

Preeclampsia is a major pregnancy disease, explained partly by genetic predispositions. STOX1, a transcription factor discovered in 2005, was the first gene directly associated with genetic forms of the disease. Alterations of STOX1 expression as well as STOX1 variants have also been associated to Alzheimer's disease. These observations make of this gene a putative therapeutic target. Area covered: Two major isoforms (STOX1A and STOX1B) are encoded by the gene and are theoretically able to compete for the same binding site, while only the most complete (STOX1A) is supposed to be able to activate gene expression. This makes the ratio between STOX1A and STOX1B as well as their position inside the cell (nucleus or cytoplasm) crucial to understand how STOX1 functions. STOX1 appears to have multiple gene targets, especially in pathways connected to inflammation, oxidative stress, and cell cycle. Expert opinion: STOX1-directed therapies, could be directed either towards its targets (genes or pathways), or directly at STOX1. For this the addressing of STOX1 to various cell compartments could theoretically be modified; also it could be possible of altering the balance between the two isoforms, through selectively inhibiting one of them, possibly improving the outcomes in severe preeclampsia.

S100A4 and P53 in myocardial collagen fibers of hypertrophic cardiomyopathy : Expression and clinical significance

OBJECTIVE

The purpose of this work is to investigate the expression of S100A4 and P53 and their correlation with myocardial collagen fibers in hypertrophic cardiomyopathy (HCM).

PATIENTS AND METHODS

Myocardial tissue obtained from 10 patients undergoing HCM surgery (HCM group) was compared to myocardial tissue obtained from 10 traffic accident deaths (healthy control group). Collagen volume fractions were visualized and compared using sirius red F3B(SR) staining. Immunohistochemistry S-P and in situ hybridization techniques were used to test the different expressions of S100A4, P53 proteins, and their mRNA. Imaging and statistical methods were used for quantitative analysis.

RESULTS

The collagen volume fraction in the HCM group was significantly higher than that in the control group. The integral optical density values of S100A4 and P53 in cardiomyocytes of the HCM group were also significantly higher than in the control group.

CONCLUSION

The increased content of collagen fibers and overexpression of S100A4 and P53 may play an important role in myocardial fibrosis of HCM, and they can be used in future HCM research. Blockade of S100A4 may have therapeutic potential in HCM by attenuating cardiac fibrosis.

Novel inflammatory biomarkers in primary hyperparathyroidism

OBJECTIVE

Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and increased risk of cardiovascular disease (CVD). The aim of the study was to investigate systemic levels of pro-inflammatory proteins that previously have not been examined in patients with PHPT. The selection of the pro-inflammatory biomarkers included in this study, MMP9, S100A4, S100A8/A9 and the receptors sCD14 and RAGE, was based on a previous microarray screen of mRNAs in adipose tissue from PHPT patients.

DESIGN

A prospective study was conducted on a total of 57 patients with PHPT and a control group of 20 healthy blood donors.

METHODS

PHPT patients with normalisation of serum calcium levels after parathyroidectomy were followed for 6 months. Forty-two patients participated in the longitudinal study, in which blood samples were taken at inclusion, and 1, 3 and 6 months after surgery.

RESULTS

We observed increased serum levels of MMP9 (P=0.029), S100A4 (P<0.001) and sCD14 (P=0.002) in the 57 patients with PHPT compared to the control-group. During 6 months of follow up, S100A4 (P=0.022) and sCD14 (0.002) decreased significantly, while serum levels of MMP9 increased (P=0.025).

CONCLUSIONS

The results demonstrate an increased inflammatory response in PHPT patients shown by elevated MMP9, S100A4 and sCD14 at inclusion. During the 6 months of follow-up, MMP9 increased further, possibly due to the tissue repair process after parathyroidectomy. S100A4 and sCD14 decreased after surgery demonstrating a partial reversal of the systemic inflammation.

High levels of metastasis-inducing S100A4 protein and treatment outcome in early rheumatoid arthritis: data from the PERAC cohort

Abstract The aim of this study was to evaluate the role of S100A4 as a biomarker in patients with early rheumatoid arthritis (RA). S100A4 levels were measured in 59 patients with early RA and in 41 healthy controls. The association between the S100A4 levels and the treatment outcome after 12 months was determined using multivariate regression analysis. Serum S100A4 levels were significantly higher in the patients with early RA than in the healthy subjects and significantly decreased after 3 months of treatment. Diseases activity at 12 months was significantly higher in female patients who had initially high levels of S100A4. Persistently high S100A4 levels predicted poor treatment outcome and S100A4 may thus represent promising biomarker for assessing treatment response in patients with RA.

The metastasis promoting protein S100A4 levels associate with disease activity rather than cancer development in patients with idiopathic inflammatory myopathies

Introduction

The aim was to evaluate S100A4 protein as a biomarker of disease activity and potential cancer development in patients with myositis.

Methods

Serum levels of S100A4 were determined in 43 dermatomyositis (DM), 39 polymyositis (PM) and 22 cancer associated myositis (CAM) patients as well as in 77 healthy controls. The associations between S100A4 levels, inflammation, disease activity, muscle strength and cancer development were evaluated.

Results

All myositis patients had significantly higher serum levels of S100A4 protein compared to healthy controls (median (IQR): 31.5 (17.4 to 59.5) versus 23.8 (14.5 to 33.7) ng/ml, P <0.05). In patients with PM, serum levels of S100A4 protein were significantly higher than in healthy controls (41.6 (24.2 to 123.1) versus 23.8 (14.5 to 33.7) ng/ml; P <0.001) as well as in patients with DM (26.7 (11.3 to 47.5) ng/ml; P <0.05). The levels of S100A4 were comparable between myositis with and without cancer. In all myositis patients, serum S100A4 levels correlated with MYOsitis disease ACTivity assessment (MYOACT) score (r = 0.34; P = 0.001), constitutional (r = 0.30; P = 0.003), pulmonary (r = 0.43; P = 0.0001) and extramuscular disease activity (r = 0.36; P = 0.0001), as well as with creatine phosphokinase (r = 0.27; P = 0.015) and lactate dehydrogenase (r = 0.37; P = 0.002) or c-reactive protein (CRP) levels (r = 0.24; P = 0.038). Multiple regression analysis showed significant association between S100A4 serum levels and extramuscular disease activity (β = 0.552; P = 0.002) in PM patients and with MYOACT (β = 0.557; P = 0.003) and CRP levels (β = 0.391; P = 0.029) in DM patients.

Conclusions

Circulating levels of S100A4 are elevated in patients with myositis and associate with several disease activity parameters, particularly with extramuscular components. No relation between S100A4 levels and presence of cancer associated myositis was found.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0468-2) contains supplementary material, which is available to authorized users.

Functional expression, characterization and application of the human S100A4 protein

Preparations utilizing monoclonal antibodies against S100A4 provide useful tools for functional studies to investigate the clinical applications of the human S100A4 protein. In the present study, human S100A4 protein was expressed in Escherichia coli (E. coli) BL21 (DE3), successfully purified by diethylaminoethyl cellulose anion-exchange chromatography and identified by western blot analysis. Soluble S100A4 bioactivity was confirmed by Transwell migration and invasion assays in the human HeLa cell line. Monoclonal antibodies (mAbs) were generated utilizing the standard hybridoma method and were validated by enzyme-linked immunosorbent assay and western blot analysis. The antibody was then used to examine human gastric carcinoma specimens by immunohistochemistry. Recombinant S100A4 was functionally expressed in E. coli and promoted the migration and invasion of HeLa cells. Four hybridoma cell lines, which secreted mAbs specifically against human S100A4 protein, were obtained. One of the four mAbs, namely 2A12D10B2, recognized human S100A4 as indicated by immunohistochemical staining of human gastric carcinoma specimens and recombinant S100A4 was functionally expressed in E. coli. The mAbs of recombinant S100A4 were suitable for detecting S100A4 expression in human tissues and for investigating the subsequent clinical applications of the protein.

S100A4 regulates the Src-tyrosine kinase dependent differentiation of Th17 cells in rheumatoid arthritis

OBJECTIVES

To evaluate the role of S100A4, a calcium-binding regulator of nonmuscle myosin assembly, for T-cell responses in rheumatoid arthritis.

METHODS

Arthritis was induced in the methylated bovine serum albumin (mBSA)-immunized mice lacking the entire S100A4 protein (S100A4KO) and in wild-type counterparts treated with short hairpin ribonucleic acid (shRNA)-lentiviral constructs targeting S100A4 (S100A4-shRNA). The severity of arthritis was evaluated morphologically. T-cell subsets were characterized by the expression of master transcription factors, and functionally by proliferation activity and cytokine production. The activity of the Scr-kinases Fyn and Lck was assessed by the autophosphorylation of C-terminal thyrosine and by the phosphorylation of the CD5 cytodomain. The interaction between S100A4 and the CD5 cytodomain was analysed by nuclear magnetic resonance spectrophotometry.

RESULTS

S100A4-deficient mice (S100A4KO and S100A4-shRNA) had significantly alleviated morphological signs of arthritis and joint damage. Leukocyte infiltrates in the arthritic joints of S100A4-deficient mice accumulated Foxp3(+) Treg cells, while the number of RORγt(+) and (pTyr705)STAT3(+) cells was reduced. S100A4-deficient mice had a limited formation of Th17-cells with low retinoic acid orphan receptor gamma t (RORγt) mRNA and IL17 production in T-cell cultures. S100A4-deficient mice had a low expression and activity of T-cell receptor (TCR) inhibitor CD5 and low (pTyr705)STAT3 (signal transducer and activator of transcription 3), which led to increased (pTyr352)ZAP-70 (theta-chain associated protein kinase of 70kDa), lymphocyte proliferation and production of IL2. In vitro experiments showed that S100A4 directly binds Lck and Fyn and reciprocally regulates their kinase activity towards the CD5 cytodomain. Spectrometry demonstrates an interaction between the CD5 cytodomain and EF2-binding sites of S100A4.

CONCLUSION

The present study demonstrates that S100A4 plays an important part in the pathogenesis of arthritis. It controls CD5-dependent differentiation of Th17 cells by regulating the activity of the Src-family kinases Lck and Fyn.

Quantitative proteome profiling of CNS-infiltrating autoreactive CD4+ cells reveals selective changes during experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a murine model of multiple sclerosis, a chronic neurodegenerative and inflammatory autoimmune condition of the central nervous system (CNS). Pathology is driven by the infiltration of autoreactive CD4(+) lymphocytes into the CNS, where they attack neuronal sheaths causing ascending paralysis. We used an isotope-coded protein labeling approach to investigate the proteome of CD4(+) cells isolated from the spinal cord and brain of mice at various stages of EAE progression in two EAE disease models: PLP139-151-induced relapsing-remitting EAE and MOG35-55-induced chronic EAE, which emulate the two forms of human multiple sclerosis. A total of 1120 proteins were quantified across disease onset, peak-disease, and remission phases of disease, and of these 13 up-regulated proteins of interest were identified with functions relating to the regulation of inflammation, leukocyte adhesion and migration, tissue repair, and the regulation of transcription/translation. Proteins implicated in processes such as inflammation (S100A4 and S100A9) and tissue repair (annexin A1), which represent key events during EAE progression, were validated by quantitative PCR. This is the first targeted analysis of autoreactive cells purified from the CNS during EAE, highlighting fundamental CD4(+) cell-driven processes that occur during the initiation of relapse and remission stages of disease.

Functionally active rat S100A4 from a polymerase chain reaction-synthesized gene expressed in soluble form in Escherichia coli

S100A4 protein is associated with Ca²⁺-dependent regulation of intracellular activities and is significant in the invasion, growth and metastasis of cancer. In order to express rat S100A4 functionally and identify its biological activity following purification, an S100A4 gene fragment was optimized and fully synthesized via overlapping polymerase chain reaction. The gene was inserted into the prokaryotic expression vector, pBV220, with phage λ P_RP_L promoters following confirmation by DNA sequencing. The pBV220-S100A4 plasmid was constructed and transformed into Escherichia coli DH5α. Following temperature induction, rat S100A4 was overexpressed and the protein was observed to be located in the supernatant of the lysates, which was ~30–40% of the total protein within the host. The protein was isolated and purified by metal-chelate affinity chromatography. High purity protein (>98% purity) was obtained and in vitro western blot analysis identified that the recombinant S100A4 was able to bind to the antibody against wild-type S100A4. The bioactivity of the recombinant protein was detected via Transwell migration and invasion assays. The polyclonal antibody of rat S100A4 protein was prepared for rabbit immunization and exhibited similar efficacies when compared with commercial S100A4. Therefore, rat S100A4 was functionally expressed in E. coli; thus, the production of active recombinant S100A4 protein in E. coli may further aid with the investigation and application of S100A4.

Update: biomarkers for idiopathic inflammatory myopathies

PURPOSE OF REVIEW

Establishing diagnoses and distinguishing active disease from chronic injury remain significant clinical challenges in idiopathic inflammatory myopathies (IIM). Recent 'discovery' approaches utilizing novel genomic and proteomic techniques have revealed candidate molecular biomarkers to augment clinical and classical histological data.

RECENT FINDINGS

Whole blood and serum Type 1 interferons (IFN-1) and IFN-1 inducible genes are gaining traction as disease biomarkers in IIM. IFNβ is emerging as a disease activity marker specifically for dermatomyositis. Recently, molecules associated with innate immune-cell function, including TLR-3, high mobility group box (HMGB)-1, B7 Homolog 1, S100A4, and resistin have been detected in tissues of dermatomyositis patients. Serum Interleukin-17 (IL-17) and IL-23 correlate with active disease in early IIM. Antibodies recognizing the Survival Motor Neuron complex have been newly identified in a subset of patients with polymyositis. Protein aggregates are potential disease activity sensors for inclusion body myositis. Skin and lung harbor potential biomarkers for IIM.

SUMMARY

Recent advances in understanding the pathogenesis of IIM have led to discovery of molecules that are candidate biomarkers of disease activity. Type 1 interferon and myeloid-cell signatures are leading candidate markers for use in IIM activity monitoring.

Halofuginone and other febrifugine derivatives inhibit prolyl-tRNA synthetase

Febrifugine, one of the fifty fundamental herbs of traditional Chinese medicine, has been characterized for its therapeutic activity whilst its molecular target has remained unknown. Febrifugine derivatives have been used to treat malaria, cancer, fibrosis, and inflammatory disease. We recently demonstrated that halofuginone (HF), a widely studied derivative of febrifugine, inhibits the development of Th17-driven autoimmunity in a mouse model of multiple sclerosis by activating the amino acid response pathway (AAR). Here we show that HF binds glutamyl-prolyl-tRNA synthetase (EPRS) inhibiting prolyl-tRNA synthetase activity; this inhibition is reversed by the addition of exogenous proline or EPRS. We further show that inhibition of EPRS underlies the broad bioactivities of this family of natural products. This work both explains the molecular mechanism of a promising family of therapeutics, and highlights the AAR pathway as an important drug target for promoting inflammatory resolution.

Potential role for S100A4 in the disruption of the blood-brain barrier in collagen-induced arthritic mice, an animal model of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease associated with chronic inflammation of the joints. RA has been shown to increase the morbidity of and mortality due to cardiovascular and cerebrovascular diseases. We recently reported that cerebrovascular permeability was increased in mice with collagen-induced arthritis (CIA), an animal model of RA. S100A4, a member of the S100 family, is up-regulated in synovial fluid and plasma from RA patients. This study was aimed at evaluating a role of S100A4 in the mediation of blood-brain barrier (BBB) dysfunction in CIA mice. CIA was induced by immunization with type II collagen in mice. Cerebrovascular permeability was assessed by measurement of sodium fluorescein (Na-F) levels in the brains of control and CIA mice. Serum S100A4 concentrations in control and CIA mice were measured by enzyme-linked immunosorbent assays (ELISA). Accumulation of Na-F in the brain and serum levels of S100A4 were increased in CIA mice. Increased S100A4 levels in the serum are closely correlated with hyperpermeability of the cerebrovascular endothelium to Na-F. We investigated whether S100A4 induces BBB dysfunction using mouse brain capillary endothelial cells (MBECs). S100A4 decreased the transendothelial electrical resistance and increased Na-F permeability in the MBECs. S100A4 reduced the expression of occludin, a tight junction protein, and stimulated p53 expression in MBECs. These findings suggest that S100A4 increases paracellular permeability of MBECs by decreasing expression levels of occludin, at least in part, via p53. The present study highlights a potential role for S100A4 in BBB dysfunction underlying cerebrovascular diseases in patients with RA.