Histidine-Rich Glycoprotein Suppresses the S100A8/A9-Mediated Organotropic Metastasis of Melanoma Cells

The dissection of the complex multistep process of metastasis exposes vulnerabilities that could be exploited to prevent metastasis. To search for possible factors that favor metastatic outgrowth, we have been focusing on secretory S100A8/A9. A heterodimer complex of the S100A8 and S100A9 proteins, S100A8/A9 functions as a strong chemoattractant, growth factor, and immune suppressor, both promoting the cancer milieu at the cancer-onset site and cultivating remote, premetastatic cancer sites. We previously reported that melanoma cells show lung-tropic metastasis owing to the abundant expression of S100A8/A9 in the lung. In the present study, we addressed the question of why melanoma cells are not metastasized into the brain at significant levels in mice despite the marked induction of S100A8/A9 in the brain. We discovered the presence of plasma histidine-rich glycoprotein (HRG), a brain-metastasis suppression factor against S100A8/A9. Using S100A8/A9 as an affinity ligand, we searched for and purified the binding plasma proteins of S100A8/A9 and identified HRG as the major protein on mass spectrometric analysis. HRG prevents the binding of S100A8/A9 to the B16-BL6 melanoma cell surface via the formation of the S100A8/A9 complex. HRG also inhibited the S100A8/A9-induced migration and invasion of A375 melanoma cells. When we knocked down HRG in mice bearing skin melanoma, metastasis to both the brain and lungs was significantly enhanced. The clinical examination of plasma S100A8/A9 and HRG levels showed that lung cancer patients with brain metastasis had higher S100A8/A9 and lower HRG levels than nonmetastatic patients. These results suggest that the plasma protein HRG strongly protects the brain and lungs from the threat of melanoma metastasis.

Differential Regulation of Circulating Soluble Receptor for Advanced Glycation End Products (sRAGEs) and Its Ligands S100A8/A9 Four Weeks Post an Exercise Intervention in a Cohort of Young Army Recruits

Apart from its beneficial effects on cardiovascular risk factors, an anti-inflammatory effect of exercise is strongly implicated. Yet, data regarding the effect of an exercise intervention on healthy individuals are limited and contradictory. The present study aimed to investigate the effects of a physical activity intervention on the soluble form of the receptor for advanced glycation end products (sRAGEs) and its ligands S100A8/A9. A total of 332 young army recruits volunteered and 169 completed the study. The participants underwent the standard basic training of Greek army recruits. IL-6, IL-1β, S100A8/A9, and sRAGEs were measured at the beginning and at the end of the training period. Primary rodent adult aortic smooth muscle cells (ASMCs) were analyzed for responsiveness to direct stimulation with S100A8/A9 alone or in combination with sRAGEs. At the end of the training period, we observed a statistically significant reduction in S100A8/A9 (630.98 vs. 472.12 ng/mL, p = 0.001), IL-1β (9.39 [3.8, 44.14] vs. 5.03 [2.44, 27.3] vs. pg/mL, p = 0.001), and sRAGEs (398.38 vs. 220.1 pg/mL, p = 0.001). IL-6 values did not change significantly after exercise. S100A8/A9 reduction was positively correlated with body weight (r = 0.236 [0.095, 0.370], p = 0.002) and BMI (r = 0.221 [0.092, 0.346], p = 0.004). Direct stimulation of ASMCs with S100A8/A9 increased the expression of IL-6, IL-1β, and TNF-α and, in the presence of sRAGEs, demonstrated a dose-dependent inhibition. A 4-week military training resulted in significant reduction in the pro-inflammatory cytokines IL-1β and S100A8/A9 complex. The observed reduction in sRAGEs may possibly reflect diminished RAGE axis activation. Altogether, our findings support the anti-inflammatory properties of physical activity.

S100A8 may govern hyper-inflammation in severe COVID-19

The coronavirus disease 2019 (COVID-19) pandemic threatens human species with mortality rate of roughly 2%. We can hardly predict the time of herd immunity against and end of COVID-19 with or without success of vaccine. One way to overcome the situation is to define what delineates disease severity and serves as a molecular target. The most successful analogy is found in BCR-ABL in chronic myeloid leukemia, which is the golden biomarker, and simultaneously, the most effective molecular target. We hypothesize that S100 calcium-binding protein A8 (S100A8) is one such molecule. The underlying evidence includes accumulating clinical information that S100A8 is upregulated in severe forms of COVID-19, pathological similarities of the affected lungs between COVID-19 and S100A8-induced acute respiratory distress syndrome (ARDS) model, homeostatic inflammation theory in which S100A8 is an endogenous ligand for endotoxin sensor Toll-like receptor 4/Myeloid differentiation protein-2 (TLR4/MD-2) and mediates hyper-inflammation even after elimination of endotoxin-producing extrinsic pathogens, analogous findings between COVID-19-associated ARDS and pre-metastatic lungs such as S100A8 upregulation, pulmonary recruitment of myeloid cells, increased vascular permeability, and activation coagulation cascade. A successful treatment in an animal COVID-19 model is given with a reagent capable of abrogating interaction between S100A8/S100A9 and TLR4. In this paper, we try to verify our hypothesis that S100A8 governs COVID-19-associated ARDS.

Circulating Calprotectin as a Biomarker of COVID-19 Severity

INTRODUCTION

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although demographic and clinical parameters such as sex, age, comorbidities, genetic background and various biomarkers have been identified as risk factors, there is an unmet need to predict the risk and onset of severe inflammatory disease leading to poor clinical outcomes. In addition, very few mechanistic biomarkers are available to inform targeted treatment of severe (auto)-inflammatory conditions associated with COVID-19. Calprotectin, also known as S100A8/S100A9, MRP8/14 (Myeloid-Related Protein) or L1, is a heterodimer involved in neutrophil-related inflammatory processes. In COVID-19 patients, calprotectin levels were reported to be associated with poor clinical outcomes such as significantly reduced survival time, especially in patients with severe pulmonary disease.

AREAS COVERED

Pubmed was searched using the following keywords: Calprotectin + COVID19, S100A8/A9 + COVID19, S100A8 + COVID-19, S100A9 + COVID-19, MRP8/14 + COVID19; L1 + COVID-19 between May 2020 and 8 March 2021. The results summarized in this review provide supporting evidence and propose future directions that define calprotectin as an important biomarker in COVID-19.

EXPERT OPINION

Calprotectin represents a promising serological biomarker for the risk assessment of COVID-19 patients.

Plasma levels of S100A8/A9, histone/DNA complexes, and cell-free DNA predict adverse outcomes of immune thrombotic thrombocytopenic purpura

BACKGROUND

Immune thrombotic thrombocytopenic purpura (iTTP) is a life-threatening blood disorder, primarily resulting from autoantibodies against ADAMTS13. Infection or inflammation often precedes acute iTTP. However, the association of inflammation and inflammatory mediators with disease severity and outcome of acute iTTP is not fully assessed.

OBJECTIVES

Here, we determined plasma levels of S100A8/A9, histone/DNA complexes, citrullinated histone H3 (CitH3), and cell-free DNA (cfDNA) in a cohort of 108 acute episodes from 94 unique iTTP patients and healthy controls, and assessed the association of each of these biomarkers with the disease severity and mortality.

RESULTS

All acute iTTP patients had significantly increased plasma levels of S100A8/A9 (median 84.8, interquartile range [IQR] 31.2-157.4 µg/mL), histone/DNA complexes (median 55.7, IQR 35.8-130.8 U/mL), CitH3 (median 3.8, IQR 2.2-6.4 ng/mL), and cfDNA (median 937.7, IQR 781.3-1420.0 ng/mL) on the admission blood samples when compared with healthy controls. An increased plasma level of S100A8/A9, histone/DNA complex and cfDNA was associated with organ damage, coagulopathy, and mortality in iTTP. After being adjusted for age and history of hypertension, Cox proportional hazard regression analysis demonstrated that a hazard ratio (95% confidence interval) for an elevated plasma level of S100A8/A9, histone/DNA complexes, and cfDNA was 11.5 (1.4-90.9) (P = .021), 10.3 (2.7-38.5) (P = .001), and 12.8 (3.9-42.0) (P = .014), respectively.

CONCLUSION

These results indicate that inflammation or plasma inflammatory mediators such as S100A8/A9 or NETosis markers such as histone/DNA complexes and cfDNA may play a role in pathogenesis of iTTP, which may help stratify patients with a high risk of death during acute iTTP episodes.

Serum Calprotectin Is a Potential Marker in Patients with Asthma

BACKGROUND

Calprotectin is the major cytosolic protein in neutrophil granulocytes. Although asthma is known to cause eosinophilic inflammation, some patients with asthma have non-eosinophilic inflammation, which is characterized by local neutrophilic inflammation. The aim of this study was to assess calprotectin expression levels in a mouse model of asthma, and to observe the relationship of serum calprotectin level and clinical variables in patients with asthma.

METHODS

Mice were sensitized and challenged with 10 μg and 20 μg of Aspergillus fumigatus, respectively; mice treated with saline were used as a control. The levels of calprotectin were determined using enzyme-linked immunosorbent assay, immunoblotting, and immunohistochemical analysis. The serum levels of calprotectin were also assessed in patients with asthma. The relationship between calprotectin and clinicopathological characteristics was determined.

RESULTS

Calprotectin, S100A8, and S100A9 expression was elevated in the mouse lungs, calprotectin levels were higher in the serum of patients with asthma (n = 33) compared with those of healthy individuals (n = 28). Calprotectin levels correlated with forced expiratory volume in one second/forced vital capacity (r = -0.215, P = 0.043), smoke amount (r = 0.413, P = 0.017), body mass index (r = -0.445, P = 0.000), and blood neutrophil percentage (r = 0.300, P = 0.004) in patients with asthma.

CONCLUSION

Our data suggest that calprotectin could potentially be used as a biomarker for asthma.

Serum myeloid-related protein 8/14 is a potential predictor of diabetic kidney disease

BACKGROUND

Myeloid-related protein 8/14 (MRP8/14) is secreted by macrophages and formed by MRP8 and MRP14, which is closely related to vascular inflammation. Chronic vascular inflammation plays a significant role in the development and progression of diabetic kidney disease (DKD). This study aims to investigate the relationship between MRP8/14 and DKD.

METHODS

A total of 80 individuals with type 2 diabetes were divided into four groups, according to the baseline urinary albumin/creatinine ratio (ACR) levels Serum concentrations of MRP8/14 were measured by ELISA. The clinical variables were obtained through physical examination, illness history, or laboratory evidence.

RESULTS

As DKD worsened, the level of serum MRP8/14 increased gradually, and MRP8/14 has a significantly positive correlation with ACR (r = 0.349, P = 0.002), body mass index (BMI) (r = 0.288, P = 0.009), serum creatinine (Cre) (r = 0.392, P < 0.001), blood urine nitrogen (BUN) (r = 0.333, P = 0.003), systolic blood pressure (SBP) (r = 0.301, P = 0.007), and a negative correlation with the estimated glomerular filtration rate (eGFR) (r = -0.478, P < 0.001). Logistic regression analysis showed that age, Cre, eGFR, ACR, and MRP8/14 were associated with the progression of DKD (P < 0.05).

CONCLUSIONS

The serum MRP8/14 is correlated significantly with the progression of DKD, suggesting that MRP8/14 may be an independent predictor of the progression of DKD.

The Association Between S100A8/A9 and the Development of Very Late Stent Thrombosis in Patients With Acute Myocardial Infarction

Very late stent thrombosis (VLST) is a rare but serious complication following percutaneous coronary intervention (PCI). S100A8/A9 plays an important role in thrombosis through modulating the inflammatory response. This observational study aimed to reveal the association between S100A8/A9 and VLST. Continuous blood samples were collected from patients at both the time of index PCI for acute myocardial infarction (AMI) and the time of PCI for VLST (VLST group) or follow-up coronary angiography (AMI group). In all, 56 patients were selected in each group from a cohort of 8476 patients and other 112 individuals who underwent health checkups (normal control [NC] group) were selected as controls. Serum levels of S100A8/A9 and high sensitivity C-reactive protein (hs-CRP) were tested and compared. The mean level of S100A8/A9 was 3754.4 ± 1688.9 ng/mL during index PCI and increased to 5517.8 ± 2650.9 ng/mL at the time of VLST; in the AMI group, S100A8/A9 level was 2434.9 ± 1243.4 ng/mL during index PCI and decreased to 1568.2 ± 772.1 ng/mL during follow-up, similar to that detected in the NC group (1618.2 ± 641.4 ng/mL). Of note, S100A8/A9 levels showed significant increases during VLST when compared to its own levels during index PCI, which was different from the changes of hs-CRP. Higher serum levels of S100A8/A9 are associated with the development of VLST.

Prospective evaluation of S100A12 and S100A8/A9 (calprotectin) in dogs with sepsis or the systemic inflammatory response syndrome

Pattern recognition receptors (e.g., S100A12 or S100A8/A9) hold promise as inflammatory biomarkers. We prospectively determined and compared serum S100A12 and S100A8/A9 concentrations in dogs with sepsis (n = 11) or systemic inflammatory response syndrome (SIRS; n = 8) over a 3-d period with each other, healthy controls (n = 50), and other clinical and clinicopathologic variables. Serum S100A12 and S100A8/A9 concentrations were significantly higher in dogs with sepsis or SIRS (all p < 0.05) at the time of hospital admission (day 1) compared to healthy controls, with no differences between patient groups. However, septic dogs had significantly lower serum S100A12 concentrations on day 2 and day 3 (both p < 0.05) compared to dogs with SIRS. Likewise, dogs with sepsis had significantly lower S100A8/A9 concentrations on day 2 (p < 0.05). Neither serum S100A12 nor S100A8/A9 concentrations were associated with survival to discharge. Our results suggest a differential expression of the S100/calgranulins between dogs with sepsis and those with SIRS. Serum S100A12 or S100A8/A9 concentration at the time of hospital admission did not differentiate dogs with sepsis from those with SIRS, but the trend of S100/calgranulin concentrations during the following 24-48 h may be a useful surrogate marker for differentiating sepsis from SIRS.

Observational study on Swedish plaque psoriasis patients receiving narrowband-UVB treatment show decreased S100A8/A9 protein and gene expression levels in lesional psoriasis skin but no effect on S100A8/A9 protein levels in serum

S100A8 and S100A9 proteins are highly upregulated in patients with psoriasis and have been proposed as potential biomarkers for psoriasis. The present study was designed to analyze the effect of narrowband ultraviolet B therapy on these proteins.

S100A8, S100A9 gene expression and S100A8/A9 heterocomplex protein levels were analyzed in lesional and non-lesional skin before and after narrowband-UVB treatment in patients with chronic plaque type psoriasis. In addition, disease severity was measured by psoriasis area and severity index (PASI) and serum protein levels of S100A8/A9 were repeatedly analyzed. Narrowband-UVB treatment significantly reduced S100A8, S100A9 gene expression and S100A8/A9 protein levels in lesional skin while serum levels showed no significant change. No correlation between PASI and serum S100A8/A9 protein levels was found. These results implicate a role of S100A8/A9 in the anti-inflammatory effect of narrowband-UVB. Serum S100A8/A9 levels do not respond to treatment suggesting that serum S100A8/A9 does not originate from psoriasis skin keratinocytes. Serum S100A8/A9 levels do not correlate with PASI questioning serum S100A8/A9 as a biomarker for psoriasis skin activity.

Trial Registration: DRKS 00014817.

Correlation between systemic S100A8 and S100A9 levels and severity of diabetic retinopathy in patients with type 2 diabetes mellitus

AIMS

S100A8 and S100A9 are myeloid-related damage-associated molecular patterns (DAMPs) primarily involved in the modulation of innate immune response to cellular injury. This study evaluated the correlation between circulating concentrations of S100A8 and S100A9 proteins with the severity of diabetic retinopathy (DR) in patients with type 2 diabetes (T2DM).

METHODS

T2DM patients with HbA1c levels >7%, fasting blood glucose >126 mg/dl and history of diabetes were included in this study. DR severity was graded based on ETDRS and Gloucestershire classifications. Plasma samples were evaluated for S100A8 and S100A9 levels using ELISA.

RESULTS

In this comparative study, DR patients (n = 89) had increased plasma S100A8 and S100A9 proteins compared to age-matched T2DM controls (n = 28), which was directly related to the severity of DR. Female DR subjects had increased S100A8 expression compared to their male counterparts. Substantial retention of S100A8 and S100A9 production was seen in DR patients above 50 years of age. Duration of T2DM was not found to affect protein levels, however T2DM onset at >50 years old significantly increased S100A8 and S100A9 concentrations.

CONCLUSIONS

Our findings suggest that systemic circulation levels of S100A8 and S100A9 are correlated with the progression of DR in T2DM patients, indicating their potential role in DR pathogenesis.

Circulating S100 proteins effectively discriminate SLE patients from healthy controls: a cross-sectional study

S100 proteins are currently being investigated as potential diagnostic and prognostic biomarkers of several cancers and inflammatory diseases. The aims of this study were to analyse the plasma levels of S100A4, S100A8/9 and S100A12 in patients with incomplete systemic lupus erythematosus (iSLE), in patients with established SLE and in healthy controls (HCs) and to investigate the potential utility of the S100 proteins as diagnostic or activity-specific biomarkers in SLE. Plasma levels were measured by ELISA in a cross-sectional cohort study of 44 patients with SLE, 8 patients with iSLE and 43 HCs. Disease activity was assessed using the SLEDAI-2K. The mean levels of all S100 proteins were significantly higher in SLE patients compared to HCs. In iSLE patients, the levels of S100A4 and S100A12 but not S100A8/9 were also significantly higher compared to HCs. There were no significant differences in S100 levels between the iSLE and SLE patients. Plasma S100 proteins levels effectively discriminated between SLE patients and HCs. The area under the curve (AUC) for S100A4, S100A8/9 and S100A12 plasma levels was 0.989 (95% CI 0.976-1.000), 0.678 (95% CI 0.563-0.792) and 0.807 (95% CI 0.715-0.899), respectively. S100 levels did not differentiate between patients with high and low disease activity. Only the S100A12 levels were significantly associated with SLEDAI-2K and with cSLEDAI-2K. S100 proteins were significantly higher in SLE patients compared HCs and particularly S100A4 could be proposed as a potential diagnostic biomarker for SLE.

Faecal but not serum calprotectin levels look promising in predicting active disease in Behçet's syndrome patients with gastrointestinal involvement

OBJECTIVES

The faecal calprotectin (FC) test is widely used as a non-invasive method for identifying intestinal inflammation. A recent study suggested FC may help to diagnose gastrointestinal involvement of Behçet's syndrome (GIBS). We aimed to determine whether FC helps to distinguish active from inactive intestinal involvement in GIBS.

METHODS

We tried to contact 70 GIBS patients registered in our tertiary multidisciplinary clinic. We prospectively collected faecal specimens and serum from 39 GIBS patients who gave informed consent assessing calprotectin and CRP levels followed by a colonoscopy. We included 47 Crohn's disease (CD) patients as controls. Active disease was defined as having ulcer/s on colonoscopy. We filled the Disease Activity Index for Intestinal Behçet's Disease (DAIBD) and Crohn's Disease Activity Index (CDAI). The cut-off for positive FC was defined as ≥150 μg/g.

RESULTS

Ulcers were detected in 12/39 GIBS patients. Sensitivity and specificity of the FC test for active disease was 91.7 (95%CI:61.5-99.8) and 74.1% (95%CI:53.7-88.9). Median FC and CRP levels and DAIBD scores were higher among patients with ulcers, whereas serum calprotectin and CDAI scores were not. A negative FC test was the only significant predictor of remission (OR:37.04, 95%CI:2.4-561.6; p=0.009) on multivariate analysis. Among CD patients, 16/25 active patients and 3/22 patients in endoscopic remission had a positive FC test (OR:11, 95%CI:11-49).

CONCLUSIONS

FC, but not serum calprotectin seems to be a useful non-invasive tool for assessing disease activity in GIBS. Whether the presence of oral ulcers can cause false positive results remains to be studied.

Serum Markers of Necrotizing Enterocolitis: A Systematic Review

OBJECTIVE

The aim of the study was to systematically review the diagnostic utility of serum biomarkers for the diagnosis of necrotizing enterocolitis (NEC).

METHODS

We conducted an electronic and manual search of the available evidence. We included studies reporting data on the diagnostic accuracy of "serum" biomarkers for the diagnosis of NEC, available until January 2016.

RESULTS

We selected 22 studies from the 1296 articles retrieved. Only S100 A8/A9 protein and apolipoprotein-CII showed high sensitivity (100% and 96.4%, respectively) and specificity (90% and 95%, respectively) in the studies using Bell stage II NEC as target condition. High sensitivity and specificity were reported for interleukin-10 (100% and 90%), interleukin1-receptor antagonist (100% and 91.7%), intestinal fatty acid-binding protein (100% and 91%) and ischemia-modified albumin (94.7% and 92%), when tested to predict the evolution from definite to advanced NEC. Given the amount of uncertainty, the limited availability of data and heterogeneity among the populations in the different studies, we were unable to perform a meta-analysis. Major concerns about the applicability stemmed from the spectrum of patients enrolled and the inclusion of diseases different from Bell stage ≥2 NEC as target conditions.

CONCLUSIONS

We identified only few markers with good diagnostic accuracy and found an overall low quality of the studies on serum NEC biomarkers. In conclusion, data supporting their use are insufficient.

Phagocyte-specific S100A8/A9 is upregulated in primary Sjögren's syndrome and triggers the secretion of pro-inflammatory cytokines in vitro

OBJECTIVES

To determine the role of S100A8/A9 in the pathogenesis of primary Sjögren's syndrome (pSS).

METHODS

The serum levels of S100A8/A9 were determined in pSS patients and healthy controls by ELISA. The expression of S100A8/A9 in salivary glands was assessed by immunohistochemistry. The phenotype of S100A8+ and S100A9+ cells was identified using double immunofluorescence. The effects of S100A8/A9 on cytokine production by peripheral blood mononuclear cells (PBMCs) from pSS patients were determined in vitro by flow cytometry. The effects of pro-inflammatory cytokines on S100A8/A9 secretion were additionally investigated in vitro by ELISA in PBMCs from pSS patients and control subjects.

RESULTS

Serum levels of S100A8/A9 were significantly increased in pSS patients compared to healthy controls. The tissular expression of S100A8 and S100A9, identified in professional phagocytes (neutrophils, monocytes and plasmacytoid dendritic cells), was increased in the salivary glands of pSS patients and correlated with focus score. In vitro, recombinant S100A8/A9 increased the production of IL-1β, IL-6, TNF-α, IFN-γ, IL-10, IL-17A and IL-22 by PBMCs. The S100A8/A9-induced increase in TNF-α production in pSS patients was significant relative to controls. Furthermore, IL-1β, TNF-α, IL-6, and IL-17A stimulated release of S100A8/A9 from PBMCs in pSS patients.

CONCLUSIONS

S100A8/A9 is increased in pSS patients contributing to the in vitro increased production of pro-inflammatory cytokines. As such, S100A8/A9 in concert with other cytokines might contribute to the pathogenesis of pSS.

A Plaque Disruption Index Identifies Patients with Non-STE-Type 1 Myocardial Infarction within 24 Hours of Troponin Positivity

Background

Markers of plaque destabilization and disruption may have a role in identifying non-STE- type 1 Myocardial Infarction in patients presenting with troponin elevation. We hypothesized that a plaque disruption index (PDI) derived from multiple biomarkers and measured within 24 hours from the first detectable troponin in patients with acute non-STE- type 1 MI (NSTEMI-A) will confirm the diagnosis and identify these patients with higher specificity when compared to individual markers and coronary angiography.

Methods

We examined 4 biomarkers of plaque destabilization and disruption: myeloperoxidase (MPO), high-sensitivity interleukin-6, myeloid-related protein 8/14 (MRP8/14) and pregnancy-associated plasma protein-A (PAPP-A) in 83 consecutive patients in 4 groups: stable non-obstructive coronary artery disease (CAD), stable obstructive CAD, NSTEMI-A (enrolled within 24 hours of troponin positivity), and NSTEMI-L (Late presentation NSTEMI, enrolled beyond the 24 hour limit). The PDI was calculated and the patients’ coronary angiograms were reviewed for evidence of plaque disruption. The diagnostic performance of the PDI and angiography were compared.

Results

Compared to other biomarkers, MPO had the highest specificity (83%) for NSTEMI-A diagnosis (P<0.05). The PDI computed from PAPP-A, MRP8/14 and MPO was higher in NSTEMI-A patients compared to the other three groups (p<0.001) and had the highest diagnostic specificity (87%) with 79% sensitivity and 86% accuracy, which were higher compared to those obtained with MPO, but did not reach statistical significance (P>0.05 for all comparisons). The PDI had higher specificity and accuracy for NSTEMI-A diagnosis compared to coronary angiography (P<0.05).

Conclusions

A PDI measured within 24 hour of troponin positivity has potential to identify subjects with acute Non-ST-elevation type 1 MI. Additional evidence using other marker combinations and investigation in a sufficiently large non-selected cohort is warranted to establish the diagnostic accuracy of the PDI and its potential role in differentiating type 1 and type 2 MI in patients presenting with troponin elevation of uncertain etiology.

Low pretreatment levels of myeloid-related protein-8/14 and C-reactive protein predict poor adherence to treatment with tumor necrosis factor inhibitors in juvenile idiopathic arthritis

Two thirds of patients with juvenile idiopathic arthritis (JIA) treated with tumor necrosis factor (TNF)-alpha inhibitors respond initially, but only about one third of patients achieve clinical remission at follow-up. We evaluated the 1-year response and long-term treatment adherence to TNF inhibitor treatment in JIA patients naive to biologics and investigated if baseline myeloid-related protein (MRP)-8/14 and C-reactive protein (CRP) were predictive of treatment response. One hundred fifty-two patients were included in a unicenter observational, prospective study from 2002 to 2015, excluding patients with systemic-onset JIA. One-year treatment response was evaluated by American College of Rheumatology-pediatric (ACR-ped) and by the number of patients achieving inactive disease (ID). Medical charts were reviewed for reasons of treatment withdrawal. After one year of treatment ACR-ped 30, 50, 70, and 90 were achieved by 61, 55, 38, and 10 % of the patients, and 23 % achieved a status of ID. Treatment adherence: 51 % withdrew from treatment due to lack of clinical effect, while 32 % continued treatment or withdrew due to disease remission. Increased MRP-8/14 concentrations at treatment initiation was associated with ID after 1 year (OR 1.55, CI 1.06-2.25, p = 0.02). Treatment withdrawal due to lack of effect was associated with low baseline levels of both MRP-8/14 (685 vs. 1235 ng/ml, p < 0.001) and CRP (0.75 vs. 2.73 mg/l, p < 0.001), verified by multivariable logistic regression analysis (OR 0.51, CI 0.34-0.77/OR 0.63, CI 0.48-0.83). In conclusion, an association was found between ID after 1 year of treatment and increased baseline levels of MRP-8/14. Furthermore, low baseline MRP-8/14 and CRP concentrations were associated with treatment withdrawal due to lack of clinical effect.

Klotho and S100A8/A9 as Discriminative Markers between Pre-Renal and Intrinsic Acute Kidney Injury

Early detection and accurate differentiation of the cause of AKI may improve the prognosis of the patient. However, to date, there are few reliable biomarkers that can discriminate between pre-renal and intrinsic AKI. In this study, we determined whether AKI is associated with altered serum and urinary levels of Klotho, S100A8/A9 (an endogenous ligand of toll-like receptor 4), and neutrophil gelatinase-associated lipocalin (NGAL), which may allow differentiation between pre-renal and intrinsic AKI. A volume-depleted pre-renal AKI model was induced in male Sprague Dawley rats fed a low-salt diet (0.03%) without water 96 h before two intraperitoneal (IP) injections of furosemide (20 mg/kg) at a 24 h interval. In contrast, in the cisplatin-induced intrinsic AKI model, animals were given a single IP injection of cisplatin (5 mg/kg). All of the animals were euthanized 72 h after the first IP injection. Serum and urinary levels of Klotho, S100A8/A9, and NGAL were measured using an enzyme-linked immunosorbent assay. We also performed a proof-of-concept cross-sectional study to measure serum and urinary biomarkers in 61 hospitalized patients with established AKI. Compared to the intrinsic AKI group, the pre-renal AKI group showed a marked depression in urinary Klotho levels (13.21±17.32 vs. 72.97±17.96 pg/mL; P = 0.002). In addition, the intrinsic AKI group showed marked elevation of S100A8/A9 levels compared to the pre-renal AKI group (2629.97±598.05 ng/mL vs. 685.09±111.65 ng/mL; P = 0.002 in serum; 3361.11±250.86 ng/mL vs. 741.72±101.96 ng/mL; P = 0.003 in urine). There was no difference in serum and urinary NGAL levels between the pre-renal and intrinsic AKI groups. The proof-of-concept study with the hospitalized AKI patients also demonstrated decreased urinary Klotho in pre-renal AKI patients and increased urinary S100A8/A9 concentrations in intrinsic AKI patients. The attenuation of urinary Klotho and increase in urinary S100A8/A9 may allow differentiation between pre-renal and intrinsic AKI.

[Expression of myeloid-related protein complex in association with circulating endothelial cells in children with acute Kawasaki disease]

OBJECTIVE

To investigate the expression of myeloid-related protein complex (MRP-8/14) in children with acute Kawasaki Disease (KD).

METHODS

A total of 41 children with acute KD and 40 age- and sex-matched control children with upper respiratory tract infection were recruited. Serum levels of MRP-8/MRP-14 complex were measured by ELISA, messenger ribonucleic acid (mRNA) abundance of MRP-8 and MRP-14 in circulating granulocytes and monocytes was determined by RT-PCR, and the number of circulating endothelial cells was determined by flow cytometry.

RESULTS

When the analysis was stratified according to the presence or absence of coronary artery ectasia in the KD patient group, serum levels of MRP-8/MRP-14 complex, MRP-8 and MRP-14 mRNA abundance in granulocytes, and the number of circulating endothelial cells were all significantly higher in KD patients with coronary artery ectasia than in KD patients without coronary artery ectasia (P<0.05). Serum levels of MRP-8/MRP-14 complex were positively correlated with the number of endothelial cells in the circulation (r=0.69, P<0.05).

CONCLUSIONS

Serum levels of MRP-8/MRP-14 complex are elevated in a positive association with the number of circulating endothelial cells in KD children with coronary artery ectasia, suggesting a causative role in the development of coronary artery lesions.

S100A8/A9 as a biomarker for synovial inflammation and joint damage in patients with rheumatoid arthritis

S100A8 and S100A9 are major leukocyte proteins, known as damage-associated molecular patterns, found at high concentrations in the synovial fluid of patients with rheumatoid arthritis (RA). A heterodimeric complex of S100A8/A9 is secreted by activated leukocytes and binds to Toll-like receptor 4, which mediates downstream signaling and promotes inflammation and autoimmunity. Serum and synovial fluid levels of S100A8/A9 are markedly higher in patients with RA than in patients with osteoarthritis or miscellaneous inflammatory arthritis. Serum levels of S100A8/A9 are significantly correlated with clinical and laboratory markers of inflammation, such as C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and the Disease Activity Score for 28 joints. Significant correlations have also been found between S100A8/A9 and radiographic and clinical assessments of joint damage, such as hand radiographs and the Rheumatoid Arthritis Articular Damage score. In addition, among known inflammatory markers, S100A8/A9 has the strongest correlation with total sum scores of ultrasonography assessment. Furthermore, baseline levels of S100A8/A9 are independently associated with progression of joint destruction in longitudinal studies and are responsive to change during conventional and biologic treatments. These findings suggest S100A8/A9 to be a valuable diagnostic and prognostic biomarker for RA.

Leukocyte and serum S100A8/S100A9 expression reflects disease activity in ANCA-associated vasculitis and glomerulonephritis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) commonly results in glomerulonephritis, in which neutrophils and monocytes have important roles. The heterodimer calprotectin (S100A8/S100A9, mrp8/14) is a Toll-like receptor-4 ligand found in neutrophils and monocytes and is elevated in inflammatory conditions. By immunohistochemistry of renal biopsies, patients with focal or crescentic glomerular lesions were found to have the highest expression of calprotectin and those with sclerotic the least. Serum levels of calprotectin as measured by ELISA were elevated in patients with active AAV and the levels decreased but did not normalize during remission, suggesting subclinical inflammation. Calprotectin levels in patients with limited systemic disease increased following treatment withdrawal and were significantly elevated in patients who relapsed compared with those who did not. As assessed by flow cytometry, patients with AAV had higher monocyte and neutrophil cell surface calprotectin expression than healthy controls, but this was not associated with augmented mRNA expression in CD14(+) monocytes or CD16(+) neutrophils. Thus, serum calprotectin is a potential disease biomarker in patients with AAV, and may have a role in disease pathogenesis.

High serum S100A8/A9 levels and high cardiovascular complication rate in type 2 diabetics with ultrasonographic low carotid plaque density

AIMS

S100A8/A9 complex is an inflammation-associated biomarker, which binds toll-like receptor 4 and was associated with the receptor for advanced glycation end-products. S100A8 and S100A9 were accumulated in atherosclerotic lesions. High serum levels of S100A8/A9 are associated with acute coronary syndrome and atherosclerosis in type 2 diabetes mellitus (T2DM). However, association between serum S100A8/A9 levels and vulnerable plaque remains unclear. The present study investigated the relation between serum S100A8/A9 levels and relative plaque density (RPD) of the carotid artery determined by ultrasonography in T2DM.

METHODS

The study subjects were 72 consecutive T2DM outpatients (males/females=42/30), who underwent the carotid artery ultrasonography. RPD in the carotid artery was calculated by the formula; RPD=[density of the carotid plaque/density of vessel lumen]. Serum levels of adiponectin and S100A8/A9 were measured.

RESULTS

The median RPD was 2.1. Patients with low RPD (≤2.1) were significantly more likely to have metabolic syndrome, nephropathy, coronary artery disease, and peripheral artery disease, and higher levels of S100A8/A9, S100A8/A9-to-adiponectin ratio, and uric acid, compared to those with high RPD (>2.1).

CONCLUSIONS

T2DM patients with low RPD had higher prevalence of metabolic syndrome, cardiovascular diseases and higher serum S100A8/A9 levels, compared to those with high RPD.

Three-month treatment with pioglitazone reduces circulating levels of S100A8/A9 (MRP8/14) complex, a biomarker of inflammation, without changes in body mass index, in type 2 diabetics with abdominal obesity

We measured circulating S100A8/A9 (MRP8/14) complex levels before and after 3-month treatment with pioglitazone in type 2 diabetic patients. The results showed that pioglitazone reduced circulating S100A8/A9 complex levels, without changing body mass index, in type 2 diabetic patients with abdominal obesity.

S100A8 cellular distribution in normal epithelium, hyperplasia, dysplasia and squamous cell carcinoma and its concentration in serum

OBJECTIVE

To investigate the function of S100A8, a member of the calcium-binding S100 protein family, in oral tumorigenesis. We analyzed its cellular distribution and its serum level in patients with squamous cell carcinoma and normal controls.

STUDY DESIGN

We investigated the histopathologic features by tissue microarrays (TMAs) including 8 normal, 66 hyperplastic and dysplastic and 26 oral squamous cell carcinoma (OSCC) tissue cores. The serum level of S100A8 was measured by an enzyme-linked immunosorbent assay using 33 healthy volunteers, 20 patients with hyperproliferative lesions and 23 patients with OSCC.

RESULTS

The TMA analysis resulted in different findings. The strongest expression of S100A8 was found in severe dysplasias and carcinoma in situ. In tumor tissue an increased expression occurred only focally. In the normal tissue cores the epithelium showed a moderate reaction, but basal and parabasal cells were completely negative. The serum levels of S100A8 were marginally reduced in cancer patients. The expression between healthy controls and patients with hyperproliferative lesions displayed no difference.

CONCLUSION

The expression of S100A8 is helpful only in the transition from severe dysplastic tissue to cancer.

Proteomic study of sera from patients with bladder cancer: usefulness of S100A8 and S100A9 proteins

To effectively obtain tumour-specific markers, fractionated proteins obtained using reversed-phase high-performance liquid chromatography for patient-matched pre- and postoperative sera from bladder cancer patients were compared by two-dimensional gel electrophoresis. The usefulness of the identified proteins was confirmed immunohistochemically. S100A8 and S100A9 were identified as tumour-associated proteins. The increased immunoreactive expression of S100A8 protein was associated with bladder wall muscle invasion of the tumour and cancer-specific survival (p<0.05), and the increased immunoreactive expression of S100A9 protein was associated with the tumour grade (p<0.05). In addition, increased expressions of both proteins was associated with recurrence-free survival at a median follow-up of 32.9 months (both p<0.05). On multivariate analysis, the expression of S100A8 was a significant predictor of recurrence (p<0.05). These findings may help to identify biologically aggressive tumors and, thus, patients who might benefit from more intensive adjuvant therapy.

Effect of human immunodeficiency virus infection on S100A8/A9 inhibition of peripheral neutrophils oxidative metabolism

Neutrophils are endowed with a highly active oxidative metabolism that is crucial for their antimicrobial functions but can produce oxidative conditions disruptive to the host. Opportunistic infections associated with HIV disease and ex vivo studies of neutrophils from HIV patients suggest that neutrophil dysfunctions significantly contribute to HIV disease. The calcium-binding proteins S100A8 and S100A9 are abundant cytosolic constituents of human neutrophils. Our previous work has shown that S100A8 and S100A9 inhibit neutrophil oxidative metabolism. In this study, we tested the hypothesis that neutrophils from HIV infected subjects respond differently to S100A8 and S100A9 when compared to neutrophils isolated from control HIV naive subjects. Neutrophils, freshly isolated from whole blood, were tested in a 96-well plate assay for their ability to oxidize the DCFH-DA probe. The neutrophils from HIV+ and HIV- subjects were stimulated with LPS and inhibited with recombinant S100A8 and S100A9. Our data indicate that when compared to neutrophils isolated from HIV- subjects, neutrophils from HIV+ subjects display an exaggerated response to LPS and a diminished response to S100A8 and S100A9 inhibition. Our data support our hypothesis and signify that, in HIV disease, dysregulated neutrophil responses to endotoxins stimulation and S100A8/A9 inhibition may contribute to a higher risk for oxidative stress associated ailments. The mechanism for the observed differences in neutrophil response and their biological significance in the course of HIV disease should be addressed in further studies.

[S100A8, S100A9 and S100A12 proteins in rheumatoid arthritis]

Although S100 proteins represent 40% of the neutrophil cytoplasmic proteins, their physiological and pathological functions are still unclear. S100A8, S100A9 and S100A12 protein concentrations are dramatically enhanced in synovial fluid and synovium of patients suffering from rheumatoid arthritis. Their expression seems to correlate with disease activity and joint damage. These proteins are likely involved in rheumatoid arthritis pathogenesis by enhancing extracellular matrix proteolysis, autoimmunity and inducing the pseudotumoral phenotype of the synoviocytes in rheumatoid arthritis. S100A8, S100A9 and S100A12 assessment will probably constitute a relevant tool for rheumatoid arthritis diagnosis and will improve inflammatory arthritides management.

S100A8/A9: a potential new diagnostic aid for acute appendicitis

OBJECTIVES

Diagnosing acute appendicitis is a daunting clinical challenge, as there is no single test that reliably distinguishes acute appendicitis from other etiologies of acute abdominal pain. In this study, the authors examined whether circulating levels of S100A8/A9 could be useful as a marker to aid in the diagnosis of acute appendicitis.

METHODS

Plasma samples from emergency department (ED) patients with acute abdominal pain (n=181) were tested using an immunoassay for S100A8/A9.

RESULTS

The sensitivity and specificity for S100A8/A9 in diagnosing acute appendicitis were estimated to be 93% (95% confidence interval [CI]=81% to 97%) and 54% (95% CI=45% to 62%), respectively. Negative predictive value (NPV) was 96% (95% CI=89% to 99%), and positive predictive value (PPV) was 37% (95% CI=28% to 47%). Performance characteristics of elevated white blood cell (WBC) count were also estimated: sensitivity 63% (95% CI=47% to 76%), specificity 67% (95% CI=59% to 75%), NPV 86% (95% CI=78% to 91%), and PPV 36% (95% CI=26% to 47%).

CONCLUSIONS

This is the first report exploring the relationship between circulating S100A8/A9 and acute appendicitis and establishes proof of concept for this biomarker as a diagnostic test for acute appendicitis. Further studies are indicated to optimize the use of this biomarker, in conjunction with other established approaches.

S100A8, S100A9, and the S100A8/A9 complex in circulating blood are not associated with prostate cancer risk-A re-evaluation study

BACKGROUND

To evaluate the diagnostic performance of plasma S100A8, S100A9, and the S100A8/A9 complex as novel markers to discriminate between benign and malignant prostatic diseases as recently suggested for S100A9.

METHODS

The study included 90 prostate cancer (PCa) patients (pN0M0, n = 50; pN1M0, n = 27; M1, n = 13), 50 controls without PCa, and six patients within 72 hr after radical prostatectomy for repeated measurements. The S100 proteins were analyzed with specific ELISAs. Comparisons were made to the prostate-specific antigen (tPSA) and the ratio of free to tPSA (%fPSA).

RESULTS

The plasma concentrations of the S100 proteins in controls had either significantly higher values (S100A8; P = 0.020) or the tendency to higher values compared with the results in PCa patients. Differences between the three PCa groups were almost negligible. No correlation could be found between S100 protein levels and PSA concentration (r(s) = -0.110 to 0.433, P = 0.317-0.433) or prostate volume (r(s) = -0.038 to 0.018, P = 0.676-0.844). Tumor stage and tumor grade had no observed effect on S100 protein concentrations. After prostatectomy, there were discordant elimination kinetics for PSA and the S100 proteins, as the S100 proteins partially increased while PSA continuously decreased. Analyses of receiver-operating curves showed that, compared with PSA, S100A8, S100A9, and S100A8/A9 did not improve the differentiation between patients with and without PCa, while the discrimination ability was significantly lower than that of %fPSA.

CONCLUSIONS

Our re-evaluation study showed that S100A8, S100A9, and the complex S100A8/A9 were less indicative than %fPSA and that they are not suitable to replace PSA.

Elevated serum levels of calcium-binding S100 proteins A8 and A9 reflect disease activity and abnormal differentiation of keratinocytes in psoriasis

BACKGROUND

The expression of calcium-binding S100 molecules organized within the epidermal differentiation complex on chromosome 1q21 is disturbed in hyperproliferative skin diseases such as psoriasis.

OBJECTIVES

We studied whether serum levels of S100 proteins A8 (S100A8) and A9 (S100A9) are elevated in psoriasis, correlated their amounts with disease activity and identified potential cellular sources.

METHODS

Serum obtained from psoriasis patients or from healthy individuals was studied for S100A8 and S100A9 levels by enzyme-linked immunosorbent assay. Data were correlated to disease activity as reflected by the Psoriasis Area and Severity Index (PASI). Cellular sources of S100A8 and S100A9 were identified by in situ hybridization and immunohistochemistry of lesional psoriatic and nonlesional, nonpsoriatic skin.

RESULTS

A significant increase of S100A8/S100A9 serum levels was found in patients with psoriasis compared with healthy controls. Grading the patients into two groups of severity, individuals with a PASI of <15 showed serum levels of 705+/-120 ng mL-1 (mean+/-SEM, n=18), those with a PASI of >or=15 showed levels of 1315+/-150 ng mL-1 (n=32) while controls presented with 365+/-50 ng mL-1. Performing in situ hybridization of lesional psoriatic skin we detected a dramatic induction of both S100A8 and S100A9 mRNA and protein primarily in the suprabasal layers of the epidermis while expression was negligible in nonlesional, nonpsoriatic interfollicular epidermis.

CONCLUSIONS

Our data demonstrate that hyperproliferation and abnormal differentiation of psoriatic skin is associated with a massive upregulation and secretion of S100A8 and S100A9, suggesting not only a prominent role of these molecules during intracellular calcium-dependent signalling but also implying distinct extracellular functions.

The Response of the Novel Pro-Inflammatory Molecules S100A8/A9 to Exercise

Exercise shares many similarities with the acute phase response of inflammatory diseases. Recently, elevated serum levels of the novel pro-inflammatory molecules of the S100 protein family, S100A8 and S100A9, have been associated with various inflammatory diseases. The present study was conducted to assess their potential roles as inflammatory markers in monitoring the exercise-induced immune response. Seventeen male subjects of different training status performed a marathon run. Furthermore 13 subjects (10 male, 3 female) performed three different treadmill tests: strenuous (STE), moderate (MTE), and downhill (DTE). S100A8/A9 complexes were measured by ELISA, while white blood cell count (WBC) and C-reactive protein (CRP) were used as markers of the inflammatory response. Serum creatine kinase (CK) concentration was determined as a marker for muscle damage. After marathon S100A8/A9 increased dramatically during the early post-exercise period and returned to resting levels one day after the run. A similar pattern was found for WBC, while CK and CRP reached their maximum on the day after the run. Moreover, S100A8/A9 release was higher in the subgroup of well-trained athletes. The kinetic of the S100A8/A9 release after the treadmill tests depended on exercise intensity and was prolonged after eccentric exercise. In summary, the present results indicate that the novel pro-inflammatory molecules S100A8/A9 are very early and sensitive markers of the exercise-induced inflammatory response. Further investigations are necessary to evaluate the applicability of S100A8/A9 for monitoring the training process and to elucidate the dependence on training status.

Expression of myeloid-related protein-8 and -14 in patients with acute Kawasaki disease

OBJECTIVES

This study investigated patients with acute Kawasaki disease (KD) to validate myeloid-related protein (MRP)-8/MRP-14 as a marker of disease activity and severity of coronary artery lesion development.

BACKGROUND

Both MRP-8 and -14, which are S100-proteins secreted by activated neutrophils and monocytes, bind specifically to endothelial cells and induce thrombogenic and inflammatory responses in a variety of disease conditions.

METHODS

We investigated 61 patients with acute KD and examined sequential changes in serum levels of MRP-8/MRP-14, messenger ribonucleic acid (mRNA) expression of MRP-8 and -14 in circulating granulocytes and monocytes, and amounts of MRP-8/MRP-14 bound to circulating endothelial cells.

RESULTS

The serum MRP-8/MRP-14 levels as well as mRNA expressions of MRP-8 and -14 in granulocytes were strongly upregulated during the early stage of acute KD, and decreased dramatically within 24 h of intravenous immune globulin therapy (p < 0.05) in 45 responders. In contrast, in 16 nonresponders both of these increased after the initial treatment. The number of MRP-8/MRP-14-positive circulating endothelial cells was higher in patients with acute KD than in control patients and increased significantly by 2 weeks after the onset of KD, especially in patients in whom coronary artery lesions developed.

CONCLUSIONS

We show for the first time that MRP-8/MRP-14 are exclusively secreted by granulocytes in patients with acute KD, and intravenous immune globulin treatment suppresses their gene expression. Serum levels of MRP-8/MRP-14 may be useful markers of disease activity, and the levels of MRP-8/MRP-14-positive circulating endothelial cell may predict the severity of vasculitis, confirming an important role for distinct inflammatory reactions in endothelium.

Calcium-binding proteins S100A8 and S100A9 as novel diagnostic markers in human prostate cancer

PURPOSE

S100 proteins comprise a family of calcium-modulated proteins that have recently been associated with epithelial tumors. We examined the expression of two members of this family, S100A8 and S100A9, together with the S100 receptor RAGE (receptor for advanced glycation end products) in human prostate adenocarcinomas and in prostatic intraepithelial neoplasia.

EXPERIMENTAL DESIGN

Tissue specimens of 75 patients with organ-confined prostate cancer of different grades were analyzed by immunohistochemistry for expression of S100A8, S100A9, and RAGE. In addition, in situ hybridization of S100A8 and S100A9 was done for 20 cases. An ELISA was applied to determine serum concentrations of S100A9 in cancer patients compared with healthy controls or to patients with benign prostatic hyperplasia (BPH).

RESULTS

S100A8, S100A9, and RAGE were up-regulated in prostatic intraepithelial neoplasia and preferentially in high-grade adenocarcinomas, whereas benign tissue was negative or showed weak expression of the proteins. There was a high degree of overlap of S100A8 and S100A9 expression patterns and of S100A8 or S100A9 and RAGE, respectively. Frequently, a gradient within the tumor tissue with an increased expression toward the invaded stroma of the prostate was observed. S100A9 serum levels were significantly elevated in cancer patients compared with BPH patients or healthy individuals.

CONCLUSION

Our data suggest that enhanced expression of S100A8, S100A9, and RAGE is an early event in prostate tumorigenesis and may contribute to development and progression or extension of prostate carcinomas. Furthermore, S100A9 in serum may serve as useful marker to discriminate between prostate cancer and BPH.

Differential expression and response to anti-TNFα treatment of infiltrating versus resident tissue macrophage subsets in autoimmune arthritis

Synovial macrophages play a pivotal role in the pathogenesis of chronic autoimmune arthritis by contributing to local inflammation and tissue damage and are therefore a primary target for therapeutic intervention. The aim of the present study was to investigate in more detail the relative contribution of different synovial macrophage subsets with potentially different inflammatory or anti-inflammatory functions by analysing the two most frequent forms of human autoimmune arthritis, spondyloarthropathy (SpA) and rheumatoid arthritis (RA). Both infiltrating macrophages from peripheral blood expressing myeloid-related proteins (MRP) 8 and 14, and resident tissue macrophages expressing CD163 were abundant in inflamed synovium. Whereas the global number of synovial macrophages was similar in both diseases, infiltrating macrophages were increased in the RA lining layer in contrast with resident tissue macrophages, which were more frequently observed in SpA. Soluble MRP8/MRP14 complexes, which were secreted locally in the joint during the infiltration process, were increased in the serum of arthritis patients and, in contrast with soluble CD163 shed from resident tissue macrophages, correlated well with global inflammatory parameters. Treatment in vivo with anti-TNFalpha had a rapid and pronounced effect on the infiltration of MRP-positive macrophages into tissues, as evidenced by histopathological analysis and serum MRP8/MRP14 levels. Taken together, these data support an important role for infiltrating versus resident tissue macrophages in human autoimmune synovitis and indicate that macrophage products such as soluble MRP8/MRP14 complexes are valuable biomarkers for the experimental and clinical monitoring of specific disease mechanisms in vivo.

Early recruitment of phagocytes contributes to the vascular inflammation of giant cell arteritis

Vascular inflammation in giant cell arteritis is generally described as a process involving dendritic cells, T-lymphocytes, and effector tissue macrophages. Less is known about the contribution of phagocytes that are recruited early, such as monocytes and neutrophils. These cells express and secrete pro-inflammatory S100 proteins which directly activate endothelial cells. In this study the expression of S100A8/S100A9 and S100A12, pro-inflammatory proteins specific for early recruited phagocytes, was studied in biopsies from 36 patients with giant cell arteritis. In addition, serum concentrations of these proteins were analysed in serum samples from 42 patients and 35 healthy controls. The S100A8/S100A9 complex was found to be abundant in the adventitia and media in affected arteries. Besides neutrophils, cells expressing these proteins belonged to a pro-inflammatory subtype of CD68-positive monocytes. In contrast, S100A12 expression was restricted to neutrophils that were found around the vasa vasorum within the adventitial layer. Both S100A8/S100A9 and S100A12 serum concentrations were significantly higher in patients with giant cell arteritis than in healthy controls. In conclusion, recently recruited phagocytes expressing pro-inflammatory S100 proteins take part in the vascular inflammation of giant cell arteritis. They may play important roles at the vasa vasorum of affected vessels, which represent sites of entry for recruited inflammatory cells. These data indicate that phagocytes within the adventitia and media contribute to the process of inflammation via release of the pro-inflammatory S100 proteins S100A8, S100A9, and S100A12.

Increased serum levels of MRP-8/14 in type 1 diabetes induce an increased expression of CD11b and an enhanced adhesion of circulating monocytes to fibronectin

The recruitment of monocytes from the bloodstream is crucial in the accumulation of macrophages and dendritic cells in type 1 diabetic pancreases. Adhesion via integrins to endothelium and extracellular matrix proteins, such as fibronectin (FN), and the production of myeloid-related protein (MRP)-8, -14, and -8/14 by recently transmigrated monocytes are thought to be instrumental in such recruitment. We determined the FN-adhesive capacity and integrin expression of monocytes of type 1 and type 2 diabetic patients and related them to the subjects' serum levels of MRP-8, -14 and -8/14. Monocytes of type 1 diabetic patients displayed an increased adhesion to fibronectin in comparison with type 2 patients and healthy control subjects but had a normal expression of the FN binding integrins CD29, CD49a, CD49d, and CD49e (although CD11b and CD18 expression was increased). MRP-8/14, which was increased in the sera of type 1 diabetic patients, induced healthy donor monocytes to adhere to FN and upregulate CD11b expression in a dosage-dependent manner. The observed MRP-induced increased adhesion of monocytes to FN and upregulation of CD11b most likely contributed to a facilitated accumulation of monocytes and monocyte-derived cells at the site of inflammation, in this case the pancreatic islets.

High expression of myeloid-related proteins 8 and 14 characterizes an inflammatorily active but ineffective response of macrophages during leprosy

Macrophages are decisive cells for the course of leprosy as they phagocytose Mycobacterium leprae and have the potential to influence the specific immune response. Expression and release of the myeloid-related protein (MRP) 8 and MRP14 (S100A8 and S100A9) characterize a proinflammatory subtype of macrophage that is prominent in, for example, murine infection with lack of a T helper 1 cell response and in certain highly active chronic inflammations of mice and humans. We investigated cutaneous biopsies of the different forms of leprosy (41 untreated patients) including leprosy reaction type 1 (reversal reaction) and type 2 (erythema nodosum leprosum) (n = 18) for expression of MRP8 and MRP14 by subtypes of macrophages. Concomitantly we determined serum levels of MRP8 and MRP14 by sandwich enzyme-linked immunosorbent assay. Expression of MRP8 and MRP14 by CD68-positive macrophages was low in tuberculoid leprosy and rose significantly in borderline tuberculoid leprosy and especially in multibacillary forms, there being expressed by mycobacteria-loaded foam cells. A significant rise of MRP8 and MRP14 expression also occurred in lepra reactions compared to the corresponding non-reactional forms. In type 2 reactions this additional increase was associated with a significant elevation of serum levels. In type 1 it was associated with expression of MRP8 and MRP14 by epitheloid and giant cells, which so far were considered not to express both proteins. In conclusion, we present evidence that the two prominent proteins MRP8 and MRP14 can be re-expressed in vivo by tissue macrophages in chronic infection, that their increased expression is characteristic for a macrophage subtype associated with high inflammatory but low antimycobacterial activity in the absence of a T helper 1 response, and that their significant rise in serum during erythema nodosum leprosum bears diagnostic and pathophysiological relevance.

Myeloid related proteins MRP8/MRP14 may predict disease flares in juvenile idiopathic arthritis

OBJECTIVE

An unsolved problem in juvenile idiopathic arthritis (JIA) is to identify patients at special risk for relapse. It is important to adjust anti-inflammatory and immunosuppressive therapy to the children's actual disease activity especially in times of remission. Our aim was to analyze if the serum levels of MRP8/MRP14 are reliable predictive markers for the risk of relapse in clinically inactive juvenile idiopathic arthritis.

METHODS

Serum concentrations of MRP8/MRP14 were determined by ELISA and correlated with laboratory and clinical parameters for disease activity in patients with JIA. 29 patients with changing disease activity were followed up for a mean time of 2.9 years. Two groups of patients--one before relapse (mean 3.7 months) but without clinical signs of disease reactivation, and one in remission for 12 further months--were compared.

RESULTS

MRP8/MRP14 serum levels in patients before relapses were significantly higher than the levels in patients in stable remission for one year (662 ng/ml versus 395 ng/ml; p < 0.05). Using a cut-off for MRP8/MRP14 of 450 ng/ml the likelihood ratio for relapse was 3.7 (positive predictive value 80%), while no differences were found for C-reactive protein and erythrocyte sedimentation rate between the two groups.

CONCLUSION

MRP8/MRP14 correlate with individual disease activity in patients with JIA. Our data suggest that local disease activity may be present even months before flares become clinically apparent. Serum levels of MRP8/MRP14 can give a hint as to clinically occult disease activity, in this way helping to adjust therapy in times of low disease activity.

Monocyte activation and disease activity in multiple sclerosis. A longitudinal analysis of serum MRP8/14 levels

In active multiple sclerosis (MS) lesions macrophages expressing myeloid related protein (MRP) 8/14 are present. The aim of this study was to determine whether serum levels of MRP8/14 complexes are related to disease activity in MS. In a longitudinal study of 16 relapsing remitting (RR) MS patients that underwent monthly gadolinium diethylentriaminepenta acid (Gd-DTPA) magnetic resonance imaging (MRI), the relation between serum MRP8/14 levels and disease activity was investigated. Patients were participating in a monoclonal antibody study targeting a specific T cell population (Vbeta5.2/5.3+ T-cells). In time, within patients large variations in serum MRP8/14 levels were observed. Serum MRP8/14 levels were not related to changes in clinical disease activity or increase in Gd-DTPA lesion enhancement. Neither did comparison of active (>1 relapse in follow-up period) with inactive (0-1 relapse) MS patients reveal any differences in MRP8/14 levels. Therefore, we conclude that although MRP8/14 expression is a good histopathological marker for monocyte activation, serum levels of these proteins do not correlate with disease activity in RR MS.

Methotrexate treatment in juvenile idiopathic arthritis: when is the right time to stop?

OBJECTIVES

To investigate whether prolonged methotrexate (MTX) treatment after induction of remission influences the subsequent duration of remission in patients with juvenile idiopathic arthritis (JIA), and to analyse the usefulness of myeloid related proteins 8 and 14 (MRP8/MRP14) as predictive markers for the stability of remission at the time when MTX is withdrawn.

METHODS

Twenty five patients with oligoarticular and polyarticular JIA who received MTX to induce remission were followed up. MTX treatment was stopped after a mean of 3.8 months (group 1) or 12.6 months (group 2) after remission was documented. Differences in the number of relapses between these groups were looked for. Additionally, MRP8/MRP14 were analysed by ELISA in 22 patients.

RESULTS

No difference was found in the number of relapses between patients with prolonged or early discontinued MTX treatment. Patients who were in stable remission had significantly lower MRP levels when MTX was discontinued than patients with relapses. With a cut off point for MRP8/MRP14 at 250 ng/ml, sensitivity and specificity were 100% and 70%, respectively.

CONCLUSION

Longer duration of MTX treatment after induction of remission does not generally improve the status of remission in patients with JIA. Residual synovial inflammation seems to influence the rate of relapses after discontinuation of MTX treatment. MRP8/MRP14 indicate residual activity even in the absence of other laboratory or clinical signs of continuing inflammation. Normal serum concentrations of MRP8/MRP14 in clinical inactive arthritis may help to identify patients in whom MTX can be safely withdrawn after remission is achieved.

Calgranulins in cystic fluid and serum from patients with ovarian carcinomas

Ovarian cancer remains still associated with poor prognosis because it is diagnosed predominantly at advanced stages. Ovarian-specific tumor markers do not yet exist for early detection of the disease. At the search of diagnostic markers for ovarian cancer, proteomic-based approaches have focused on novel investigations of neoplastic processes in tumor patients. Cystic fluids of malignant and benign ovarian tumors and serum from the corresponding patients were collected and processed for two-dimensional gel electrophoresis. Proteins were visualized on the gels by silver staining. At the low molecular mass level between 10 and 20 kDa, selected protein spots were additionally processed for nanospray mass spectrometry and partial amino acid sequencing. For protein identification, the sequencing results were compared with computer information from a protein data bank. Protein patterns from cystic fluids of ovarian carcinomas differed significantly from those of benign cysts and revealed additional polypeptides at low molecular mass level between 10 and 20 kDa. Protein patterns from serum of patients with malignant ovarian tumors also contained additional polypeptides between 10 and 20 kDa that were not detected in serum from patients with benign cysts. The additional proteins in serum were present in similar electrophoretic positions compared with those found in the cystic fluid of the corresponding ovarian carcinomas. Protein spots in the range of 10-20 kDa were selected for partial amino acid sequencing. Two protein spots were identified as calgranulin A and three spots as calgranulin B. Either both proteins or only calgranulin A or B were present in cystic fluid from ovarian carcinomas and serum of the corresponding patients. These two proteins were absent or not detectable in fluid from benign ovarian cysts and in serum from those patients. Our investigations concerning protein patterns in cystic fluid of malignant and benign ovarian tumors provide new information about alterations in protein synthesis linked to neoplastic events of the ovary. With the proteomic strategy, new tumor markers are characterized and may serve for diagnostic purposes of patients with ovarian cancer.

Expression of myeloid-related proteins 8 and 14 in systemic-onset juvenile rheumatoid arthritis

OBJECTIVE

To analyze which cellular compartments are involved in the initial phase of systemic-onset juvenile rheumatoid arthritis (JRA), and to investigate the role that myeloid-related protein 8 (MRP-8) and MRP-14, two S-100 proteins that are primarily expressed in phagocytes, play in the disease.

METHODS

Skin biopsy samples obtained during patients' acute episodes of systemic-onset JRA were analyzed by immunohistochemistry and in situ hybridization. Concentrations of MRP-8/MRP-14 in serum were determined by enzyme-linked immunosorbent assay.

RESULTS

By analyzing biopsy samples from cutaneous rashes during the initial phase of systemic-onset JRA, we discovered infiltration of leukocytes expressing MRP-8 and MRP-14. Surprisingly, keratinocytes also showed de novo synthesis of these proinflammatory proteins, indicating activation of epithelial cells during systemic-onset JRA. Serum concentrations of MRP-8/MRP-14 were 120-fold higher compared with healthy controls and approximately 12-fold higher compared with patients with other inflammatory diseases. Concentrations of MRP-8/MRP-14 in patients with systemic-onset JRA fell dramatically after remission was induced.

CONCLUSION

The exceptionally high serum levels of MRP-8 and MRP-14 in active systemic-onset JRA make them prime candidates as markers for monitoring disease activity and response to treatment. Since MRP-8/MRP-14 exhibit direct effects on leukocyte adhesion to the vascular endothelium, their extensive expression in the epidermis indicates an active role for these S-100 proteins in the initial phase of this systemic autoimmune disease.

Role of S100A8 and S100A9 in neutrophil recruitment in response to monosodium urate monohydrate crystals in the air-pouch model of acute gouty arthritis

OBJECTIVE

To examine the role of chemokines, S100A8, and S100A9 in neutrophil accumulation induced by the causative agent of gout, monosodium urate monohydrate (MSU) crystals.

METHODS

MSU crystal-induced neutrophil migration was studied in the murine air-pouch model. Release of chemokines, S100A8, S100A9, and S100A8/A9 in response to MSU crystals was quantified by enzyme-linked immunosorbent assays. Recruited cells were counted following acetic blue staining, and the subpopulations were characterized by Wright-Giemsa staining of cytospins.

RESULTS

MSU crystals induced the accumulation of neutrophils following injection in the air pouch, which correlated with the release of the chemokines CXCL1, CXCL2, CCL2, and CCL3. However, none of these was found to play an important role in neutrophil migration induced by MSU crystals by passive immunization with antibodies directed against each chemokine. S100A8, S100A9, and S100A8/A9 were also found at high levels in the pouch exudates following injection of MSU crystals. In addition, injection of S100A8, S100A9, or S100A8/A9 led to the accumulation of neutrophils in the murine air pouch, demonstrating their proinflammatory activities in vivo. Passive immunization with anti-S100A8 and anti-S100A9 led to a total inhibition of the accumulation of neutrophils. Finally, S100A8/A9 was found at high concentrations in the synovial fluid of patients with gout.

CONCLUSION

S100A8 and S100A8/A9 are essential to neutrophil migration induced by MSU crystals. These results suggest that they might be involved in the pathogenesis of gout.

New ELISA system for myeloid-related protein complex (MRP8/14) and its clinical significance as a sensitive marker for inflammatory responses associated with transplant rejection

BACKGROUND

C-reactive protein (CRP), a useful marker for inflammatory diseases, is not always sensitive to inflammatory reaction in the liver or other tissues. The aim of this study was to develop a sensitive and specific method for detecting inflammatory responses associated with transplant rejection.

METHODS

We developed a new, highly sensitive ELISA system for the measurement of serum human myeloid-related protein complex (MRP8/14), using monoclonal antibodies against MRP8/14, and applied it to specimens obtained from patients undergoing small intestine or liver transplantation.

RESULTS

This assay could detect MRP8/14 concentrations as low as 2 micro g/L. Within-run CVs were 3.7-6.1% and between-day CVs were 5.6-8.7% for MRP8/14 concentrations of 117-3300 micro g/L. Mean recovery was 104% (range, 80-128%). We observed a marked increase in serum MRP8/14 postoperatively in most recipients of transplants, followed by an increase in CRP 1-7 days after the increase in the complex. The increase in serum MRP8/14 occurred simultaneously with permeation of lymphocytes into the transplanted tissues as a result of rejection of the graft tissues.

CONCLUSIONS

Accurate measurement of serum MRP8/14 provides a useful clinical diagnostic method tool for detecting inflammation associated with rejection of transplanted tissues.

Myeloid related protein 8 and 14 secretion reflects phagocyte activation and correlates with disease activity in juvenile idiopathic arthritis treated with autologous stem cell transplantation

OBJECTIVES

To determine whether myeloid related proteins (MRP8/MRP14), a complex of two S100 proteins related to neutrophil and monocyte activation, might be used as a marker for disease activity, and as an early indicator of relapse in juvenile idiopathic arthritis.

PATIENTS AND METHODS

A group of 12 patients who underwent an autologous haematopoietic stem cell transplantation (ASCT) for refractory juvenile idiopathic arthritis (JIA) were studied. MRP8/MRP14 serum concentrations were determined by a sandwich enzyme linked immunosorbent assay (ELISA) as described. Improvement from baseline was described by a definition of improvement employing a core set of criteria as detailed previously by Giannini.

RESULTS

After ASCT, MRP8/MRP14 serum concentrations in JIA showed a positive correlation with the Child Health Assessment Questionnaire (CHAQ; r=0.80) and erythrocyte sedimentation rate (r=0.45), but not with the total leucocyte count (r=0.26). Mean MRP8/MRP14 serum concentrations dropped markedly in the first three months after ASCT (p=0.0039) and clinical parameters of disease activity such as CHAQ markedly improved (p=0.0039). During a transient relapse there was an increase in MRP8/MRP14.

CONCLUSIONS

MRP8/MRP14 serum concentration can be used as a marker for disease activity in patients who receive an ASCT for refractory JIA. This indicates a role of macrophage activation in the pathogenesis of JIA. The occurrence of MAS in three patients in this study was not preceded by significant changes in MRP8/MRP14 concentration.