[S100A8, S100A9 and S100A12 proteins in rheumatoid arthritis]

From bench to bedside: Calprotectin (S100A8/S100A9) as a biomarker in rheumatoid arthritis

S100A9/S100A8 (calprotectin), a member of the S100 protein family, has been shown to play a pivotal role in innate immunity activation. Calprotectin plays a critical role in the pathogenesis of rheumatoid arthritis (RA), as it triggers chemotaxis, phagocyte migration and modulation of neutrophils and macrophages. Higher calprotectin levels have been found in synovial fluid, plasma, and serum from RA patients. Recent studies have demonstrated better correlations between serum or plasma calprotectin and composite inflammatory disease activity indexes than c-reactive protein (CRP) or the erythrocyte sedimentation rate (ESR). Calprotectin serum levels decreased after treatment, independently of the DMARD type or strategy. Calprotectin has shown the strongest correlations with other sensitive techniques to detect inflammation, such as ultrasound. Calprotectin independently predicts radiographic progression. However, its value as a biomarker of treatment response and flare after tapering is unclear. This update reviews the current understanding of calprotectin in RA and discusses possible applications as a biomarker in clinical practice.

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.

Proteins involved in the endoplasmic reticulum stress are modulated in synovitis of osteoarthritis, chronic pyrophosphate arthropathy and rheumatoid arthritis, and correlate with the histological inflammatory score

It is now well recognized that osteoarthritis (OA) synovial membrane presents inflammatory components. The aim of this work is to provide evidence that similar inflammatory mechanisms exist in synovial membrane (n = 24) obtained from three pathologies presenting altogether an inflammatory gradient: OA, chronic pyrophosphate arthropathy (CPPA) and rheumatoid arthritis (RA). Synovial biopsies were first characterized by a histological score based on synovial hyperplasia and infiltration of lymphocytes, plasma cells, polymorphonuclear and macrophages. All biopsies were also analyzed by 2D-nano-UPLC-ESI-Q-Orbitrap for protein identification and quantification. Protein levels were correlated with the histological score. Histological score was in the range of 3 to 8 for OA, 5 to 13 for CPPA and 12 to 17 for RA. Of the 4,336 proteins identified by mass spectrometry, 51 proteins were selected for their strong correlation (p < 0.001) with the histological score of which 11 proteins (DNAJB11, CALR, ERP29, GANAB, HSP90B1, HSPA1A, HSPA5, HYOU1, LMAN1, PDIA4, and TXNDC5) were involved in the endoplasmic reticulum (ER) stress. Protein levels of S100A8 and S100A9 were significantly higher in RA compared to OA (for both) or to CPPA (for S100A8 only) and also significantly correlated with the histological score. Eighteen complement component proteins were identified, but only C1QB and C1QBP were weakly correlated with the histological score. This study highlights the inflammatory gradient existing between OA, CPPA and RA synovitis either at the protein level or at the histological level. Inflamed synovitis was characterized by the overexpression of ER stress proteins.

Efficacy, safety and cost-effectiveness of a web-based platform delivering the results of a biomarker-based predictive model of biotherapy response for rheumatoid arthritis patients: a protocol for a randomized multicenter single-blind active controlled clinical trial (PREDIRA)

BACKGROUND

Rheumatoid arthritis (RA) is one of the leading chronic inflammatory rheumatism. First-line therapy with synthetic disease-modifying antirheumatic drugs (sDMARD) is insufficiently effective in 40% of cases and these patients are treated with biotherapies. The increased use of these drugs each year is becoming a public health issue with considerable economic burden. This cost is 20 times higher than that of sDMARD. However, among patients treated with biotherapies, clinical practice shows that about one third will not respond to the selected drug. In nonresponse cases, practitioners currently have no choice but to perform an empirical switching between different treatments, because no tool capable of predicting the response or nonresponse to these molecules is currently available.

METHODS

The study is a prospective, phase III, controlled, multicenter, and randomized, single-blind (patient) clinical trial, including RA patients with a previous failure to anti-TNF therapies. The main objective is the analysis of the clinical and pharmacoeconomic impact after 6 months of treatment. Intervention arm: prescription of biotherapy (rituximab, adalimumab, abatacept) using SinnoTest® software, a prediction software based on proteomic biomarkers. Control arm: prescription of biotherapy based on current practice, without the SinnoTest® software (any biotherapy). In addition, a substudy will be carried out within this trial to generate a biobank and further analyze the proteomic profile of the patients and their modification throughout the study.

DISCUSSION

This clinical trial study will be the first validation study of a biotherapy response prediction software, bringing personalized medicine into the management of RA. We expect that the findings from this study will bring several benefits for the patient and the Health Care System.

TRIAL REGISTRATION

ClincalTrials.gov NCT04147026 . Registered on 31 October, 2019.

Blocking the interaction between S100A9 protein and RAGE V domain using S100A12 protein

The proteins S100A9 and S100A12 are associated with the human S100 calcium-binding protein family. These proteins promote interaction with target proteins and alter their conformation when they bind to calcium ions in EF-hand motifs. The V domain of RAGE (Receptor for Advanced Glycation End products) is crucial for S100A9 binding. The binding of RAGE with S100 family proteins aids in cell proliferation. In this report, we demonstrate that S100A12 protein hinders the binding of S100A9 with the RAGE V-domain. We used fluorescence and NMR spectroscopy to analyze the interaction of S100A9 with S100A12. The binary complex models of S100A9-S100A12 were developed using data obtained from 1H-15N HSQC NMR titrations and the HADDOCK program. We overlaid the complex models of S100A9-S100A12 with the same orientation of S100A9 and the RAGE V-domain. This complex showed that S100A12 protein blocks the interaction between S100A9 and the RAGE V-domain. It means S100A12 may be used as an antagonist for S100A9. The results could be favorable for developing anti-cancer drugs based on S100 family proteins.

Association between serum S100A9 levels and liver necroinflammation in chronic hepatitis B

BACKGROUND

S100A9 protein, which is recently classified as a novel damage associated molecular pattern, is released from stressed cells undergoing necrosis or secreted by living cells undergoing a stress that act as endogenous danger signal associated with infection, tissue damage and cancer. Here, we evaluated the relationship of serum S100A9 with viral replication and liver necroinflammation in patients with chronic hepatitis B (CHB) infection.

METHODS

A total of one hundred and eighty-three recruited patients with CHB infection underwent liver biopsy for grading of necroinflammation (G) and staging of fibrosis (S). Forty-nine healthy individuals were included as healthy controls (HCs). Serum S100A9 levels were determined by enzyme-linked immunosorbent assay. Correlations of serum S100A9 with viral replication and liver necroinflammation were analyzed. The receiver operating characteristic curve was used to assess the discriminating power of serum S100A9 to grade liver necroinflammation (G). Liver normal L02 cells were transfected with a HBV plasmid, and S100A9 levels were determined.

RESULTS

Serum S100A9 levels were increased in CHB patients compared to HCs. Intrahepatic immunoreactivity for S100A9 was enhanced in liver sample from CHB patients. Infection of HBV also resulted in an elevated S100A9 expression in L02 cells. Serum S100A9 was correlated with the serum HBV DNA levels. CHB patients with moderate-to-severe liver necroinflammation (G ≥ 2) showed significantly higher serum S100A9 levels than those without or with mild necroinflammation (G < 2). In patients with normal ALT levels, the area under the curve (AUC) of S100A9 for discriminating patients with moderate-to-severe necroinflammation (G ≥ 2) was 0.791 [95% confidence interval (CI), 0.670-0.913] with 91.7% sensitivity, 65.0% specificity and 78.3% accuracy. In patients with an alanine aminotransferase (ALT) < 2 upper limit of normal, the AUC of S100A9 for discriminating patients with moderate-to-severe necroinflammation (G ≥ 2) was 0.826 (95% CI, 0.729-0.923) with 87.9% sensitivity, 72.5% specificity and 80.2% accuracy.

CONCLUSIONS

HBV infection may enhance S100A9 expression. Serum S100A9 levels are correlated with viral load. Serum S100A9 has potential to discriminate the grades of liver necroinflammation, particularly in CHB patients with normal or mildly increased ALT levels.

Calprotectin in patients with chronic rheumatoid arthritis correlates with disease activity and responsiveness to methotrexate

OBJECTIVE

Calprotectin (myeloid-related protein 8/14) is elevated in inflammatory diseases and a correlation of serum calprotectin and disease activity in rheumatoid arthritis (RA) has been shown. In this study, we investigated plasma calprotectin as a disease marker in patients with chronic RA treated with methotrexate (MTX) monotherapy and compared plasma calprotectin with C-reactive protein (CRP) in this matter.

METHODS

Seventy-six patients with chronic RA were included in this open prospective study and of these 40 were included prior to initiation of MTX therapy. The patients were followed with laboratory and clinical parameters for 52-56 weeks. Plasma calprotectin was analyzed at the start of study and at various intervals. Radiographic evaluation was performed at baseline and after 17.2 months and progression in joint destruction was measured with Larsen score. The response to MTX was evaluated according to the American College of Rheumatology criteria.

RESULTS

Patients starting MTX treatment had significantly higher levels of plasma calprotectin compared to patients well established on MTX therapy (p = .008). Among the 40 patients naive to MTX, 25 responded to MTX therapy and serum calprotectin decreased significantly in these patients (p = .0007). The radiographic damage showed no relation to calprotectin.

CONCLUSIONS

Plasma calprotectin is associated with disease activity in patients with chronic RA and is more strongly correlated to MTX response compared to CRP. The role of calprotectin as a disease marker is promising and the advantages compared to CRP needs to be further investigated.

Associations between Soluble Receptor for Advanced Glycation End Products (sRAGE) and S100A12 (EN-RAGE) with Mortality in Long-term Hemodialysis Patients

Hemodialysis (HD) patients experience vascular calcification, ultimately leading to high mortality rates. Previously, we reported associations between soluble receptor for advanced glycation end products (sRAGEs) and extracellular newly identified RAGE-binding protein S100A12 (EN-RAGE) and vascular calcification. Here, we extended our observations, investigating whether these biomarkers may be useful for predicting cardiovascular morbidity and mortality in these subjects. Thus, we evaluated the relationship between sRAGE and S100A12 and mortality in long-term HD patients. This was a prospective observational cohort study in 199 HD patients from an extended analysis of our previous study. Plasma sRAGE, S100A12, comorbidities, and other traditional risk factors were investigated. The cumulative incidences for death using Cox proportional hazards regression were evaluated in multivariable analyses. The observation period was 44 months. During the observation period, 27 (13.6%) patients died. Univariate analysis demonstrated that S100A12 was correlated with diabetes (P = 0.040) and high-sensitivity C-reactive protein (hsCRP) (P = 0.006). In multivariable analyses, plasma sRAGE (hazard ratio [HR] = 1.155; 95% confidence interval [CI] = 0.612-2.183; P = 0.656) and S100A12 (HR = 0.960; 95% CI = 0.566-1.630; P = 0.881) were not associated with mortality in HD patients, although traditional predictors of mortality, including age, history of cardiovascular diseases (CVDs), and serum levels of albumin and hsCRP were related to mortality. Powerful predictors of mortality were age, CVD, and albumin levels. Plasma sRAGE and S100A12 may be weak surrogate markers for predicting all-cause mortality in patients undergoing HD, although S100A12 was partly related to diabetes and inflammation.

Synovial fluid proteome in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoinflammatory disorder that affects small joints. Despite intense efforts, there are currently no definitive markers for early diagnosis of RA and for monitoring the progression of this disease, though some of the markers like anti CCP antibodies and anti vimentin antibodies are promising. We sought to catalogue the proteins present in the synovial fluid of patients with RA. It was done with the aim of identifying newer biomarkers, if any, that might prove promising in future.

METHODS

To enrich the low abundance proteins, we undertook two approaches-multiple affinity removal system (MARS14) to deplete some of the most abundant proteins and lectin affinity chromatography for enrichment of glycoproteins. The peptides were analyzed by LC-MS/MS on a high resolution Fourier transform mass spectrometer.

RESULTS

This effort was the first total profiling of the synovial fluid proteome in RA that led to identification of 956 proteins. From the list, we identified a number of functionally significant proteins including vascular cell adhesion molecule-1, S100 proteins, AXL receptor protein tyrosine kinase, macrophage colony stimulating factor (M-CSF), programmed cell death ligand 2 (PDCD1LG2), TNF receptor 2, (TNFRSF1B) and many novel proteins including hyaluronan-binding protein 2, semaphorin 4A (SEMA4D) and osteoclast stimulating factor 1. Overall, our findings illustrate the complex and dynamic nature of RA in which multiple pathways seems to be participating actively.

CONCLUSIONS

The use of high resolution mass spectrometry thus, enabled identification of proteins which might be critical to the progression of RA.

Innate danger signals in acute injury: From bench to bedside

The description of the systemic inflammatory response syndrome (SIRS) as a reaction to numerous insults marked a turning point in the understanding of acute critical states, which are intensive care basic cases. This concept highlighted the final inflammatory response features whichever the injury mechanism is: infectious, or non-infectious such as extensive burns, traumas, major surgery or acute pancreatitis. In these cases of severe non-infectious insult, many endogenous mediators are released. Like infectious agents components, they can activate the immune system (via common signaling pathways) and initiate an inflammatory response. They are danger signals or alarmins. These molecules generally play an intracellular physiological role and acquire new functions when released in extracellular space. Many progresses brought new information on these molecules and on their function in infectious and non-infectious inflammation. These danger signals can be used as biomarkers and provide new pathophysiological and therapeutic approaches, particularly for immune dysfunctions occurring after an acute injury. We present herein the danger model, the main danger signals and the clinical consequences.

Staphylococcal enterotoxin C in synovial fluid of patients with rheumatoid arthritis

BACKGROUND

In the previous studies using the commercial ELISA kit, the existence of staphylococcal superantigens has been reported in synovial fluid of patients with rheumatoid arthritis (RA).

OBJECTIVES

This study aimed to design molecular methods to detect staphylococcal enterotoxin C in synovial fluid of patients with rheumatoid arthritis.

MATERIALS AND METHODS

In this experimental study, Staphylococcus aureus strain producing enterotoxin C was used as the reference strain. The polymerase chain reaction (PCR) was set up by design a specific pair of primers. Besides bacterial culture, 50 synovial fluid samples of patients with rheumatoid arthritis were subjected to DNA extraction, and then PCR amplification was carried out according to the protocol. All samples were examined by ELISA method for enterotoxin C. The data were descriptively analyzed.

RESULTS

The results of bacterial culture were negative for all samples. The results showed that 66% (33 cases) of samples contained entC gene and only 46% (23 cases) have also enterotoxin C. The interesting finding was that the results of ELISA and PCR were the same and have shown only 22 positive cases (44%samples) for staphylococcal enterotoxin C.

CONCLUSIONS

Based on the findings of this study, S. aureus enterotoxin C (SEC) has been detected in synovial fluid of patients with rheumatoid arthritis by PCR and ELISA methods. These valuable findings may describe the exact etiology of the RA and as well as change the methods of its diagnosis and treatment. This is the first research, which has shown the staphylococcal entC gene in synovial fluid of RA patients. However, S. aureus strains can produce more than 20 types of enterotoxins. Therefore, its involvement on rheumatoid arthritis pathogenesis makes an important challenge in the future. In this regard, further investigation on the other enterotoxins is necessary.

S100A9 promotes human lung fibroblast cells activation through receptor for advanced glycation end-product-mediated extracellular-regulated kinase 1/2, mitogen-activated protein-kinase and nuclear factor-κB-dependent pathways

S100A9 belongs to the S100 family of calcium-binding proteins and plays a key role in many inflammatory conditions. Recent studies have found that S100A9 was elevated significantly in the bronchoalveolar lavage fluid of idiopathic pulmonary fibrosis patients, and might be a biomarker for fibrotic interstitial lung diseases. However, the exact function of S100A9 in pulmonary fibrosis needs further studies. We performed this study to investigate the effect of S100A9 on human embryo lung fibroblast (HLF) proliferation and production of cytokines and collagen, providing new insights into the possible mechanism. S100A9 promoted proliferation of fibroblasts and up-regulated expression of both proinflammatory cytokines interleukin (IL)-6, IL-8, IL-1β and collagen type III. S100A9 also induced HLF cells to produce α-smooth muscle actin (α-SMA) and receptor for advanced glycation end-product (RAGE). In addition, S100A9 caused a significant increase in extracellular-regulated kinase (ERK)1/2 mitogen-activated protein kinase (MAPK) phosphorylation, while the status of p38 and c-Jun N-terminal kinase (JNK) phosphorylation remained unchanged. Treatment of cells with S100A9 also enhanced nuclear factor kappa B (NF-κB) activation. RAGE blocking antibody pretreatment inhibited the S100A9-induced cell proliferation, cytokine production and pathway phosphorylation. S100A9-mediated cell activation was suppressed significantly by ERK1/2 MAPK inhibitor and NF-κB inhibitor. In conclusion, S100A9 promoted HLF cell growth and induced cells to secret proinflammatory cytokines and collagen through RAGE signalling and activation of ERK1/2 MAPK and NF-κB pathways.

Crenotherapy modulates the expression of proinflammatory cytokines and immunoregulatory peptides in nasal secretions of children with chronic rhinosinusitis

BACKGROUND

The effect of crenotherapy on major mucosal markers of inflammation, TNF alpha, human beta-defensins 2 (hBD-2), and calprotectin, are largely unexplored in pediatric chronic rhinosinusitis (CRS). The aim of this study was to investigate the effects of crenotherapy with sulfate-sodium-chloride water on mucosal markers of inflammation in children with CRS.

METHODS

Children with CRS received 15-day crenotherapy consisting of sulfate-sodium-chloride thermal water inhalations by nasal aerosol (15 minutes/day). Concentrations of nasal mucosal markers of inflammation (TNF alpha, hBD-2, and calprotectin) were measured before and after crenotherapy. Presence of specific symptoms (nasal obstruction, nasal discharge, facial pain, sense of smell, and cough), value of symptoms score sino-nasal 5 (SN5), quality of life (QoL) score (1 [worse] to 10 [optimal]) were also assessed.

RESULTS

After crenotherapy a significant reduction was observed in TNF alpha (from 0.14 ± 0.02 to 0.08 ± 0.01; p < 0.001), calprotectin (from 2.9 ± 1.0 to 1.9 ± 0.5; p < 9.001), and hBD-2 (from 2.0 ± 0.1 to 0.9 ± 0.6; p < 0.001) concentrations. A significant (p < 0.05) reduction in number of subjects presenting symptoms of nasal obstruction (100% versus 40%), nasal discharge (33% versus 13%), facial pain (30% versus 10%), and sense of smell (60% versus 20%) was observed. A significant improvement of SN5 (from 3.07 ± 0.76 to 2.08 ± 0.42; p < 0.001) was observed after the crenotherapy. QoL also improved after crenotherapy (from 4.2 ± 1.1 to 6.6 ± 1.0; p < 0.001).

CONCLUSION

Crenotherapy induced a down-regulation of nasal mucosal inflammatory mediators in children with CRS.