Phagocyte-specific calcium-binding S100 proteins as clinical laboratory markers of inflammation

Biomarkers of postoperative delirium and cognitive dysfunction

Elderly surgical patients frequently experience postoperative delirium (POD) and the subsequent development of postoperative cognitive dysfunction (POCD). Clinical features include deterioration in cognition, disturbance in attention and reduced awareness of the environment and result in higher morbidity, mortality and greater utilization of social financial assistance. The aging Western societies can expect an increase in the incidence of POD and POCD. The underlying pathophysiological mechanisms have been studied on the molecular level albeit with unsatisfying small research efforts given their societal burden. Here, we review the known physiological and immunological changes and genetic risk factors, identify candidates for further studies and integrate the information into a draft network for exploration on a systems level. The pathogenesis of these postoperative cognitive impairments is multifactorial; application of integrated systems biology has the potential to reconstruct the underlying network of molecular mechanisms and help in the identification of prognostic and diagnostic biomarkers.

High-resolution gene expression profiling using RNA sequencing in patients with inflammatory bowel disease and in mouse models of colitis

BACKGROUND AND AIMS

Proper interpretation of data from preclinical animal studies requires thorough knowledge of the pathophysiology of both the human disease and animal models. In this study, the expression of inflammatory bowel disease [IBD]-associated genes was characterised in mouse models of colitis to examine the underlying molecular pathways and assess the similarity between the experimental models and human disease.

METHODS

RNA sequencing was performed on colon biopsies from Crohn's disease [CD] patients, ulcerative colitis [UC] patients and non-IBD controls. Genes shown to be significantly dysregulated in human IBD were used to study gene expression in colons from a piroxicam-accelerated colitis interleukin-10 knockout [PAC IL-10 k.o.], an adoptive transfer [AdTr] and a dextran sulfate sodium [DSS] colitis mouse model.

RESULTS

Of 115 literature-defined genes linked to IBD, 92 were significantly differentially expressed in inflamed mucosa of CD and/or UC patients compared with non-IBD controls. The most upregulated genes were shared by both diseases, including REG1A, LCN2, NOS2, CXCL1-2, and S100A9. Of those 92 IBD-associated genes, 71 [77%] were significantly dysregulated in PAC IL-10 k.o. mice, whereas 59 [64%] were significantly dysregulated in AdTr mice compared with wild-type controls. Some of the most upregulated genes, including S100a8-9, Nos2, and Lcn2, were shared by the colitis models and correlated with disease activity.

CONCLUSIONS

IBD and experimental murine colitis have a high degree of similarity in the colonic transcriptional profile, probably secondary to non-specific inflammatory processes. However, differences do exist between models, emphasising the need for careful selection and interpretation of qualified animal models in preclinical research.

A standardized randomized 6-month aerobic exercise-training down-regulated pro-inflammatory genes, but up-regulated anti-inflammatory, neuron survival and axon growth-related genes

There is considerable support for the view that aerobic exercise may confer cognitive benefits to mild cognitively impaired elderly persons. However, the biological mechanisms mediating these effects are not entirely clear. As a preliminary step towards informing this gap in knowledge, we enrolled older adults confirmed to have mild cognitive impairment (MCI) in a 6-month exercise program. Male and female subjects were randomized into a 6-month program of either aerobic or stretch (control) exercise. Data collected from the first 10 completers, aerobic exercise (n=5) or stretch (control) exercise (n=5), were used to determine intervention-induced changes in the global gene expression profiles of the aerobic and stretch groups. Using microarray, we identified genes with altered expression (relative to baseline values) in response to the 6-month exercise intervention. Genes whose expression were altered by at least two-fold, and met the p-value cutoff of 0.01 were inputted into the Ingenuity Pathway Knowledge Base Library to generate gene-interaction networks. After a 6-month aerobic exercise-training, genes promoting inflammation became down-regulated, whereas genes having anti-inflammatory properties and those modulating immune function or promoting neuron survival and axon growth, became up-regulated (all fold change≥±2.0, p<0.01). These changes were not observed in the stretch group. Importantly, the differences in the expression profiles correlated with significant improvement in maximal oxygen uptake (VO2max) in the aerobic program as opposed to the stretch group. We conclude that three distinct cellular pathways may collectively influence the training effects of aerobic exercise in MCI subjects. We plan to confirm these effects using rt-PCR and correlate such changes with the cognitive phenotype.

Extracellular MRP8/14 is a regulator of β2 integrin-dependent neutrophil slow rolling and adhesion

Myeloid-related proteins (MRPs) 8 and 14 are cytosolic proteins secreted from myeloid cells as proinflammatory mediators. Currently, the functional role of circulating extracellular MRP8/14 is unclear. Our present study identifies extracellular MRP8/14 as an autocrine player in the leukocyte adhesion cascade. We show that E-selectin–PSGL-1 interaction during neutrophil rolling triggers Mrp8/14 secretion. Released MRP8/14 in turn activates a TLR4-mediated, Rap1-GTPase-dependent pathway of rapid β2 integrin activation in neutrophils. This extracellular activation loop reduces leukocyte rolling velocity and stimulates adhesion. Thus, we identify Mrp8/14 and TLR4 as important modulators of the leukocyte recruitment cascade during inflammation in vivo.

MRP8/14 are actively secreted by myeloid cells during inflammation. Here the authors show that MRP8/14 play an important role in leukocyte recruitment to the inflammatory site, triggering an autocrine cascade that promotes neutrophil adhesion to the endothelium.

Host gene expression for Mycobacterium avium subsp. paratuberculosis infection in human THP-1 macrophages

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease, which causes considerable economic loss in the dairy industry and has a possible relationship to Crohn's disease (CD) in humans. As MAP has been detected in retail pasteurized milk samples, its transmission via milk is of concern. Despite its possible role in the etiology of CD, there have been few studies examining the interactions between MAP and human cells. In the current study, we applied Ingenuity Pathway Analysis to the transcription profiles generated from a murine model with MAP infection as part of a previously conducted study. Twenty-one genes were selected as potential host immune responses, compared with the transcriptional profiles in naturally MAP-infected cattle, and validated in MAP-infected human monocyte-derived macrophage THP-1 cells. Of these, the potential host responses included up-regulation of genes related to immune response (CD14, S100A8, S100A9, LTF, HP and CHCIL3), up-regulation of Th1-polarizing factor (CCL4, CCL5, CXCL9 and CXCL10), down-regulation of genes related to metabolism (ELANE, IGF1, TCF7L2 and MPO) and no significant response of other genes (GADD45a, GPNMB, HMOX1, IFNG and NQO1) in THP-1 cells infected with MAP.

Fecal calprotectin and the clinical activity index are both useful to monitor medical treatment in patients with ulcerative colitis

BACKGROUND

Non-invasive monitoring of inflammatory bowel disease is an unmet clinical need as patients in clinical remission may have residual mucosal inflammation preceding clinical relapse.

AIMS

We aimed to assess the value of fecal calprotectin and standardized clinical activity scoring to monitor disease activity in ulcerative colitis under medical treatment.

METHODS

Forty-one patients with ulcerative colitis were included in a prospective observational study. Medical treatment was guided by clinical judgement of treating physicians. Fecal calprotectin and the clinical activity index (CAI) were measured blinded to treating physicians every 2 months until the end of follow-up. Twenty-six patients received colonoscopy for clinical reason.

RESULTS

As defined by the CAI, patients were in clinical remission (63.4 %), having mild (26.8 %) or moderate (11.2 %) disease activity. Of those in clinical remission (CAI ≤ 4), 86.4 % showed residual endoscopic activity (Mayo Score ≥1). Calprotectin levels were higher in endoscopically active disease (779.0 vs 331.5 μg/g, P = 0.034) and calprotectin testing identified more patients with endoscopic disease activity (86.4 %) than the CAI (45.5 %, P = 0.034). Medical treatment was escalated in 90.2 % during the study. Values of the CAI and calprotectin correlated with therapy escalation (OR 3.94 and 3.22, respectively). Only for calprotectin, changes between two measurements were related to intensified medical treatment (OR 1.39).

CONCLUSION

Fecal calprotectin was similarly useful to the CAI to monitor disease activity of ulcerative colitis during medical treatment but identified endoscopic disease activity far more reliably. Changes of calprotectin values between measurements might indicate clinical relapse earlier than the CAI.

Identification of S100A9 as biomarker of responsiveness to the methotrexate/etanercept combination in rheumatoid arthritis using a proteomic approach

OBJECTIVES

One way to optimize the drug prescription in rheumatoid arthritis (RA) is to identify predictive biomarkers of drug responsiveness. Here, we investigated the potential "theranostic" value of proteins of the S100 family by monitoring levels of both S100A8 and S100A9 in blood samples from RA patients.

DESIGN

For proteomic analysis, peripheral blood mononuclear cells (PBMC) and serum samples were collected in patients prior to initiation of the methotrexate/etanercept (MTX/ETA) combination. Firstly, relative mass spectrometry (MS) quantification focusing on S100A8 and S100A9 proteins was carried out from PBMCs samples to identify potential biomarkers. The same approach was also performed from serum samples from responder (R) and non responder (NR) patients. Finally, to confirm these results, an absolute quantification of S100A8, S100A9 proteins and calprotectin (heterodimer of S100A8/S100A9) was carried out on the serum samples using ELISA.

RESULTS

MS analyses revealed that both S100A8 and S100A9 proteins were significantly accumulated in PBMC from responders. In contrast to PBMC, only the S100A9 protein was significantly overexpressed in the serum of R patients. Absolute quantification by ELISA confirmed this result and pointed out a similar expression level of S100A8 protein and calprotectin in sera from both R and NR groups. Thus, the S100A9 protein revealed to be predictive of MTX/ETA responsiveness, contrarily to parameters of inflammation and auto-antibodies which did not allow significant discrimination.

CONCLUSION

This is the first report of an overexpression of S100A9 protein in both PBMCs and serum of patients with subsequent response to the MTX/ETA combination. This protein thus represents an interesting biomarker candidate of therapeutic response in RA.

Blood-based candidate biomarkers of the presence of neuropsychiatric systemic lupus erythematosus in children

Objective

To examine select brain-reactive proteins for their usefulness to serve as blood-based biomarkers in the screening for neurocognitive deficits in childhood-onset systemic lupus erythematosus (cSLE-NCD).

Methods

Patients withcSLE (n=40) were studied longitudinally (month 1; month 18): working memory, psychomotor speed and visuoconstructional ability were assessed using formal neurocognitive testing to determine the presence of cSLE-NCD. Patients also completed the computerised Paediatric Automated Neuropsychological Assessment Metrics. The following brain-reactive proteins were measured in the blood: neutrophil gelatinase associated lipocalin (NGAL), S100B, S100A8/9, antibodies to NR2 glutamate receptor (aNR2-AB), ribosomal-P (aP-AB), glycoprotein-1 (aGP1-AB), and lupus anticoagulant.

Results

cSLE-NCD was present in 6 of 40 patients at baseline and 4 of 27 patients with 18-month information. aP-AB positivity was more commonly present with cSLE-NCD than without (p=0.05). aP-ABs were negatively associated with performance on tests assessing working memory, psychomotor speed and visuoconstructional ability in using formal neurocognitive testing. There were also significant negative associations between aP-AB, S100A8/9, aNR2-AB, aGP1-AB, and lupus anticoagulant and accuracy rates on select Paediatric Automated Neuropsychological Assessment Metrics subtests (p<0.05). Over time, decline in cognitive performance was more pronounced among patients with higher NGAL and aNR2-AB levels. Combinations of serum levels of S100A8/9, S100B, NGAL, aNR2-AB and aP-AB were able to identify cSLE-NCD (sensitivity: 100%; specificity 76%) in exploratory analysis.

Conclusions

Select brain-reactive proteins in the blood are associated with cognitive performance and the presence of cSLE-NCD, cross-sectionally and over time. This raises the possibility that testing of these proteins may assist with the screening of cSLE-NCD.

Proteome changes in mesenteric lymph induced by sepsis

The present study aimed to examine the changes in mesenteric lymph during the development of sepsis and to identify the distinct proteins involved, as targets for further study. The sepsis animal model was constructed by cecal ligation and puncture (CLP). The mesenteric lymph was collected from 28 adult male Sprague-Dawley rats, which were randomly divided into the following four groups (n=7 per group): CLP-6 h, CLP-24 h, sham-6 h and sham-24 h groups. Capillary high performance liquid chromatography-tandem mass spectrometry was performed to analyze the proteome in mesenteric lymph. A comprehensive bioinformatic analysis was then conducted to investigate the distinct proteins. Compared with the sham group, 158 distinct proteins were identified in the lymph samples from the CLP group. Five of these proteins associated with the same lipid metabolism pathway were selected, apolipoprotein E (ApoE), annexin A1 (Anxa1), neutrophil gelatinase-associated lipocalin (NGAL), S100a8 and S100a9. The expression of ApoE, Anxa1, NGAL, S100a8 and S100a9 were all elevated in the progression of sepsis. The five proteins were reported to be closely associated with disease development and may be a potential target for the diagnosis and treatment of sepsis. In conclusion, identifying proteome changes in mesenteric lymph provides a novel perspective to understand the pathological mechanisms underlying sepsis.

Inhibition of macrophage functions by the C-terminus of murine S100A9 is dependent on B-1 cells

The protein S100A9 plays a key role in the control of inflammatory response. The C-terminus of the murine S100A9 protein (mS100A9p) downregulates the spreading and phagocytic activity of adherent peritoneal cells. Murine peritoneal cells are constituted by macrophages and B-1 cells, and the latter exert an inhibitory effect on macrophage functions by secreting interleukin- (IL-) 10. Here, we investigated the influence of B-1 cells on the inhibitory effect evoked by mS100A9p on macrophages. mS100A9p did not alter spreading and phagocytosis either by peritoneal macrophages obtained from mice deprived of B-1 cells or by bone marrow-derived macrophages (BMDMϕ). Nevertheless, when BMDMϕ were cocultivated by direct or indirect contact with B-1 cells treated with mS100A9p, the phagocytosis by BMDMϕ was decreased, showing that the effect of mS100A9p on macrophages was modulated by B-1 cells and/or their secretory compounds. Furthermore, the inhibitory action of mS100A9p on phagocytosis by adherent peritoneal cells was abolished in cells obtained from IL-10 knockout mice. Taken together, the results show that mS100A9p has no direct inhibitory effect on macrophages; however, mS100A9p modulates B-1 cells, which in turn downregulates macrophages, at least in part, via IL-10. These data contribute to the characterization of S100A9 functions involving B-1 cells in the regulation of the inflammatory process.

The inflammation-related gene S100A12 is positively regulated by C/EBPβ and AP-1 in pigs

S100A12 is involved in the inflammatory response and is considered an important marker for many inflammatory diseases in humans. Our previous studies indicated that the S100A12 gene was abundant in the immune tissues of pigs and was significantly upregulated during infection with Haemophilus parasuis (HPS) or porcine circovirus type 2 (PCV2). In this study, the mechanism of transcriptional regulation of S100A12 was investigated in pigs. Our results showed that S100A12, CCAAT/enhancer-binding protein beta (C/EBPβ) and activator protein-1 (AP-1) genes were up-regulated in PK-15 (ATCC, CCL-33) cells when treated with LPS or Poly I: C. Additionally, the promoter activity and expression level of the S100A12 gene were significantly upregulated when C/EBPβ or AP-1 were overexpressed. We utilized electromobility shift assays (EMSA) to confirm that C/EBPβ and AP-1 could directly bind the S100A12 gene promoter. We also found that the transcriptional activity and expression levels of C/EBPβ and AP-1 could positively regulate each other. Furthermore, the promoter activity of the S100A12 gene was higher when C/EBPβ and AP-1 were cotransfected than when they were transfected individually. We concluded that the S100A12 gene was cooperatively and positively regulated by C/EBPβ and AP-1 in pigs. Our study offers new insight into the transcriptional regulation of the S100A12 gene.

In silico assessment of S100A12 monomer and dimer structural dynamics: implications for the understanding of its metal-induced conformational changes

Changes in the concentration of different ions modulate several cellular processes, such as Ca(2+) and Zn(2+) in inflammation. Upon activation of immune system effector cells, the intracellular Ca(2+) concentration rises propagating the activation signal, leading to degranulation and generation of reactive oxygen species, which increases the Zn(2+) intracellular concentration as a consequence of the cellular antioxidant machinery. In this context, S100A12 is of special interest because it is a pro-inflammatory protein expressed in neutrophils whose structure and function are modulated by both Ca(2+) and Zn(2+). The current hypothesis about its mechanism of action was built based on biochemical and crystallographic data. However, there are missing connections between molecular structure and the way in which many events are concatenated at the triggering and along the inflammatory process. In this work we use molecular dynamics simulations to describe how variations in Zn(2+) and Ca(2+) concentrations modulate the structural dynamics of the calcium-free S100A12 dimer and monomer, which was not considered a part of the mechanism of action before. Our results suggest that (i) Zn(2+) have a determinant role in the dimerization step, as well as in the unbinding of the Na(+) complexed to the N-terminal EF-hand; (ii) the N-terminal EF-hand domain is the first to bind Ca(2+), and not the C-terminal, as usually accepted; and that (iii) Ca(2+) modulates the structural dynamics of H-III.

Joining S100 proteins and migration: for better or for worse, in sickness and in health

The vast diversity of S100 proteins has demonstrated a multitude of biological correlations with cell growth, cell differentiation and cell survival in numerous physiological and pathological conditions in all cells of the body. This review summarises some of the reported regulatory functions of S100 proteins (namely S100A1, S100A2, S100A4, S100A6, S100A7, S100A8/S100A9, S100A10, S100A11, S100A12, S100B and S100P) on cellular migration and invasion, established in both culture and animal model systems and the possible mechanisms that have been proposed to be responsible. These mechanisms involve intracellular events and components of the cytoskeletal organisation (actin/myosin filaments, intermediate filaments and microtubules) as well as extracellular signalling at different cell surface receptors (RAGE and integrins). Finally, we shall attempt to demonstrate how aberrant expression of the S100 proteins may lead to pathological events and human disorders and furthermore provide a rationale to possibly explain why the expression of some of the S100 proteins (mainly S100A4 and S100P) has led to conflicting results on motility, depending on the cells used.

Effect of large colon ischemia and reperfusion on concentrations of calprotectin and other clinicopathologic variables in jugular and colonic venous blood in horses

OBJECTIVE

To determine the effect of large colon ischemia and reperfusion on concentrations of the inflammatory neutrophilic protein calprotectin and other clinicopathologic variables in jugular and colonic venous blood in horses.

ANIMALS

6 healthy horses.

PROCEDURES

Horses were anesthetized, and ischemia was induced for 1 hour followed by 4 hours of reperfusion in a segment of the pelvic flexure of the large colon. Blood samples were obtained before anesthesia, before induction of ischemia, 1 hour after the start of ischemia, and 1, 2, and 4 hours after the start of reperfusion from jugular veins and veins of the segment of the large colon that underwent ischemia and reperfusion. A sandwich ELISA was developed for detection of equine calprotectin. Serum calprotectin concentrations and values of blood gas, hematologic, and biochemical analysis variables were determined.

RESULTS

Large colon ischemia caused metabolic acidosis, a significant increase in lactate and potassium concentrations and creatine kinase activities, and a nonsignificant decrease in glucose concentrations in colonic venous blood samples. Values of these variables after reperfusion were similar to values before ischemia. Ischemia and reperfusion induced activation of an inflammatory response characterized by an increase in neutrophil cell turnover rate in jugular and colonic venous blood samples and calprotectin concentrations in colonic venous blood samples.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study suggested that large colon ischemia and reperfusion caused local and systemic inflammation in horses. Serum calprotectin concentration may be useful as a marker of this inflammatory response.

S100a8/a9 released by CD11b+Gr1+ neutrophils activates cardiac fibroblasts to initiate angiotensin II-Induced cardiac inflammation and injury

Angiotensin II induces cardiovascular injury, in part, by activating inflammatory response; however, the initial factors that trigger the inflammatory cascade remain unclear. Microarray analysis of cardiac tissue exposed to systemic angiotensin II infusion revealed that extracellular heterodimeric proteins S100a8/a9 were highly upregulated. The increase in S100a8/a9 mRNA of CD11b(+)Gr1(+) neutrophils isolated from both the peripheral blood and heart was highest on day 1 of angiotensin II infusion and decreased to baseline at day 7. Immunostaining showed that S100a8/a9 was primarily present in infiltrating CD11b(+)Gr1(+) neutrophils in the heart. The receptor for advanced glycation end products, an S100a8/a9 receptor, was expressed in cardiac fibroblasts (CFs). Microarray analysis and Bio-Plex protein array showed that treatment of CFs with recombinant S100a8/a9 activated multiple chemokine and cytokines released. Luciferase reporter assay indicated S100a8/a9-activated nuclear factor-κ B pathway in CFs. Consequently, recombinant S100a8/a9-treated CFs promoted migration of monocytes and CFs, whereas neutralizing S100a9 antibody blocked S100a9 or receptor for advanced glycation end products-suppressed cellular migration. Finally, administration of a neutralizing S100a9 antibody prevented angiotensin II infusion-induced nuclear factor-κ B activation, inflammatory cell infiltration, cytokine production, subsequent perivascular and interstitial fibrosis, and hypertrophy in heart. Our findings identify neutrophil-produced S100a8/a9 as an initial proinflammatory factor needed to trigger inflammation and cardiac injury during acute hypertension.

Measurement of urinary canine S100A8/A9 and S100A12 concentrations as candidate biomarkers of lower urinary tract neoplasia in dogs

Members of the S100 family of calcium-binding proteins (S100A8, A9, and A12; calgranulins) have been associated with inflammation and cancer in human beings. Proteins S100A8 and A9 were overexpressed in human patients with transitional cell carcinoma (TCC) and prostate carcinoma (PCA), suggesting their potential as biomarkers for diagnosing and/or predicting the progression of such neoplasms. Calgranulins have not been studied in dogs with TCC or PCA. Established in-house immunoassays were validated and found suitable for measuring S100A8/A9 and S100A12 in canine urine samples to allow the study of the role of these biomarkers in dogs with TCC or PCA. Urinary calgranulin concentrations were not affected by blood contamination (e.g., due to cystocentesis), and should be normalized against urine specific gravity or urinary creatinine concentration. Urinary calgranulin concentrations were significantly increased in 11 dogs with TCC or PCA (untreated) compared to 42 healthy dogs, and the ratio between S100A8/A9 and S100A12 was significantly higher in 11 dogs with TCC or PCA than in 10 dogs diagnosed with a urinary tract infection, suggesting that calgranulins are potential biomarkers for TCC or PCA in canine patients. The clinical utility of measuring urinary calgranulins in dogs with suspected TCC or PCA warrants further investigation.

Effects of botulinum toxin type A on expression of genes in keloid fibroblasts

BACKGROUND

Invasive growth of fibroblast cells, which is regulated by multiple biological factors, is the key event in the pathophysiology of keloid scars. Recent studies have suggested that botulinum toxin type A (BoNT-A) could inhibit invasive growth of keloids. However, the molecular mechanisms are unknown.

OBJECTIVE

The authors explore the effect of BoNT-A on the expression of genes relevant to invasive growth in keloid fibroblasts.

METHODS

With 112 genes that were relevant to invasive growth, the authors utilized microarray analysis to study messenger RNA expression profiles in keloid fibroblasts treated with BoNT-A. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to confirm the microarray results.

RESULTS

Analyses from microarray and qRT-PCR revealed that the S100A4 gene was upregulated and that the TGF-β1, VEGF, MMP-1, and PDGFA genes were downregulated in fibroblasts treated with BoNT-A.

CONCLUSIONS

The BoNT-A altered expression levels of S100A4, TGF-β1, VEGF, MMP-1, and PDGFA genes in keloid fibroblasts provide a useful clue for exploring the function of BoNT-A and finding a novel treatment for keloid scarring.

Airway symptoms and biological markers in nasal lavage fluid in subjects exposed to metalworking fluids

BACKGROUNDS

Occurrence of airway irritation among industrial metal workers was investigated. The aims were to study the association between exposures from water-based metal working fluids (MWF) and the health outcome among the personnel, to assess potential effects on the proteome in nasal mucous membranes, and evaluate preventive actions.

METHODS

The prevalence of airway symptoms related to work were examined among 271 metalworkers exposed to MWF and 24 metal workers not exposed to MWF at the same factory. At the same time, air levels of potentially harmful substances (oil mist, morpholine, monoethanolamine, formaldehyde) generated from MWF was measured. Nasal lavage fluid was collected from 13 workers and 15 controls and protein profiles were determined by a proteomic approach.

RESULTS

Airway symptoms were reported in 39% of the workers exposed to MWF although the measured levels of MWF substances in the work place air were low. Highest prevalence was found among workers handling the MWF machines but also those working in the same hall were affected. Improvement of the ventilation to reduce MWF exposure lowered the prevalence of airway problems. Protein profiling showed significantly higher levels of S100-A9 and lower levels of SPLUNC1, cystatin SN, Ig J and β2-microglobulin among workers with airway symptoms.

CONCLUSIONS

This study confirms that upper airway symptoms among metal workers are a common problem and despite low levels of MWF-generated substances, effects on airway immune proteins are found. Further studies to clarify the role of specific MWF components in connection to airway inflammation and the identified biological markers are warranted.

Calgranulins may contribute vascular protection in atherogenesis

S100A8, S100A9 and S100A12 are considered proinflammatory mediators of atherosclerosis. Known as calgranulins, they are major components of neutrophils and are upregulated in macrophages and foam cells. They influence leukocyte recruitment, and may propagate inflammation by binding TLR4 and/or receptor for advanced glycation endproducts (RAGE). However, the receptors for calgranulins remain an enigma; we have no evidence for TLR4 or RAGE activation by S100A8 or S100A12. Moreover, gene regulation studies suggest antiinflammatory functions for S100A8 and emerging reports indicate pleiotropic roles. Unlike S100A9, S100A8 effectively scavenges oxidants generated by the myeloperoxidase system in vivo, forming novel thiol modifications. S100A8 is also readily S-nitrosylated, stabilizing nitric oxide and transporting it to hemoglobin. S100A8-SNO reduces leukocyte transmigration in the vasculature. S-glutathionylation of S100A9 modifies its effects on leukocyte adhesion. Both S100A8 forms inhibit mast cell activation, at least partially by scavenging reactive oxygen species required for signaling. Conversely, S100A12 activates and sequesters mast cells. However S100A12 suppresses proinflammatory cytokine induction by SAA-activated monocytes and macrophages, and inhibits matrix metalloprotease activity. We propose that the abundance and types of cells expressing calgranulins in particular microenvironments, their relative concentrations and post-translational modifications may have distinct functional outcomes, including those that are protective, at different stages of atherogenesis.  

Vaginal epithelial cell-derived S100 alarmins induced by Candida albicans via pattern recognition receptor interactions are sufficient but not necessary for the acute neutrophil response during experimental vaginal candidiasis

Vulvovaginal candidiasis (VVC), caused by Candida albicans, affects women worldwide. Animal and clinical studies suggest that the immunopathogenic inflammatory condition of VVC is initiated by S100 alarmins in response to C. albicans, which stimulate polymorphonuclear neutrophil (PMN) migration to the vagina. The purpose of this study was to extend previous in vitro data and determine the requirement for the alarmin S100A8 in the PMN response and to evaluate pattern recognition receptors (PRRs) that initiate the response. For the former, PMN migration was evaluated in vitro or in vivo in the presence or absence of S100 alarmins initiated by several approaches. For the latter, vaginal epithelial cells were evaluated for PRR expression and C. albicans-induced S100A8 and S100A9 mRNAs, followed by evaluation of the PMN response in inoculated PRR-deficient mice. Results revealed that, consistent with previously reported in vitro data, eukaryote-derived S100A8, but not prokaryote-derived recombinant S100A8, induced significant PMN chemotaxis in vivo. Conversely, a lack of biologically active S100A8 alarmin, achieved by antibody neutralization or by using S100A9(-/-) mice, had no effect on the PMN response in vivo. In PRR analyses, whereas Toll-like receptor 4 (TLR4)- and SIGNR1-deficient vaginal epithelial cells showed a dramatic reduction in C. albicans-induced S100A8/S100A9 mRNAs in vitro, inoculated mice deficient in these PRRs showed PMN migration similar to that in wild-type controls. These results suggest that S100A8 alarmin is sufficient, but not necessary, to induce PMN migration during VVC and that the vaginal PMN response to C. albicans involves PRRs in addition to SIGNR1 and TLR4, or other induction pathways.

The LIM-only protein FHL2 attenuates lung inflammation during bleomycin-induced fibrosis

Fibrogenesis is usually initiated when regenerative processes have failed and/or chronic inflammation occurs. It is characterised by the activation of tissue fibroblasts and dysregulated synthesis of extracellular matrix proteins. FHL2 (four-and-a-half LIM domain protein 2) is a scaffolding protein that interacts with numerous cellular proteins, regulating signalling cascades and gene transcription. It is involved in tissue remodelling and tumour progression. Recent data suggest that FHL2 might support fibrogenesis by maintaining the transcriptional expression of alpha smooth muscle actin and the excessive synthesis and assembly of matrix proteins in activated fibroblasts. Here, we present evidence that FHL2 does not promote bleomycin-induced lung fibrosis, but rather suppresses this process by attenuating lung inflammation. Loss of FHL2 results in increased expression of the pro-inflammatory matrix protein tenascin C and downregulation of the macrophage activating C-type lectin receptor DC-SIGN. Consequently, FHL2 knockout mice developed a severe and long-lasting lung pathology following bleomycin administration due to enhanced expression of tenascin C and impaired activation of inflammation-resolving macrophages.

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.

Functions of S100 proteins

The S100 protein family consists of 24 members functionally distributed into three main subgroups: those that only exert intracellular regulatory effects, those with intracellular and extracellular functions and those which mainly exert extracellular regulatory effects. S100 proteins are only expressed in vertebrates and show cell-specific expression patterns. In some instances, a particular S100 protein can be induced in pathological circumstances in a cell type that does not express it in normal physiological conditions. Within cells, S100 proteins are involved in aspects of regulation of proliferation, differentiation, apoptosis, Ca2+ homeostasis, energy metabolism, inflammation and migration/invasion through interactions with a variety of target proteins including enzymes, cytoskeletal subunits, receptors, transcription factors and nucleic acids. Some S100 proteins are secreted or released and regulate cell functions in an autocrine and paracrine manner via activation of surface receptors (e.g. the receptor for advanced glycation end-products and toll-like receptor 4), G-protein-coupled receptors, scavenger receptors, or heparan sulfate proteoglycans and N-glycans. Extracellular S100A4 and S100B also interact with epidermal growth factor and basic fibroblast growth factor, respectively, thereby enhancing the activity of the corresponding receptors. Thus, extracellular S100 proteins exert regulatory activities on monocytes/macrophages/microglia, neutrophils, lymphocytes, mast cells, articular chondrocytes, endothelial and vascular smooth muscle cells, neurons, astrocytes, Schwann cells, epithelial cells, myoblasts and cardiomyocytes, thereby participating in innate and adaptive immune responses, cell migration and chemotaxis, tissue development and repair, and leukocyte and tumor cell invasion.

Calprotectin in rheumatoid arthritis : association with disease activity in a cross-sectional and a longitudinal cohort

BACKGROUND

Calprotectin is potentially a more sensitive biomarker of disease activity in rheumatoid arthritis (RA) than conventional acute-phase proteins such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) because it directly reflects inflammation in the synovium and synovial fluid rather than systemic inflammatory activity.

OBJECTIVE

The aim of this study was to evaluate relationships between serum calprotectin levels, disease activity, and response to treatment. Calprotectin was also investigated as a predictive marker of clinical response.

METHODS

This observational study included selected cohorts of patients with RA treated at La Paz University Hospital, Madrid, Spain. Associations between serum calprotectin levels and clinical and laboratory parameters were analyzed in a cross-sectional cohort of 60 patients with varying disease activity, and changes in calprotectin levels in response to treatment with infliximab were analyzed at baseline and after 3 and 6 months of treatment in a longitudinal cohort of 20 patients with very active disease.

RESULTS

In the cross-sectional cohort, calprotectin levels correlated with rheumatoid factor levels (r = 0.25; p < 0.05) but not with titers of antibodies to cyclic citrullinated peptide. Significant correlations were also observed between calprotectin levels and the 28 swollen joint count (28-SJC), Disease Activity Score based on a 28-joint count (DAS28), Simplified Disease Activity Index (SDAI), ESR, and CRP levels. In the longitudinal cohort, calprotectin levels at baseline were not predictive of response to treatment but significantly decreased during treatment in responders (p < 0.0001).

CONCLUSION

Calprotectin levels strongly correlate with clinical and laboratory assessments of joint inflammation and also decrease in response to treatment, indicating that calprotectin is a promising marker for assessment and monitoring of disease activity in patients with RA. Investigations are required to further evaluate its diagnostic, prognostic, and therapeutic potential.

Diverse activation of microglia by chemokine (C-C motif) ligand 2 overexpression in brain

Background

The chemokine (C-C motif) ligand 2 (CCL2) is a monocyte chemoattractant protein that mediates macrophage recruitment and migration during peripheral and central nervous system (CNS) inflammation.

Methods

To determine the impact of CCL2 in inflammation in vivo and to elucidate the CCL2-induced polarization of activated brain microglia, we delivered CCL2 into the brains of wild-type mice via recombinant adeno-associated virus serotype 9 (rAAV-9) driven by the chicken β-actin promoter. We measured microglial activation using histological and chemical measurement and recruitment of monocytes using histology and flow cytometry.

Results

The overexpression of CCL2 in the CNS induced significant activation of brain resident microglia. CD45 and major histocompatibility complex class II immunoreactivity significantly increased at the sites of CCL2 administration. Histological characterization of the microglial phenotype revealed the elevation of “classically activated” microglial markers, such as calgranulin B and IL-1β, as well as markers associated with “alternative activation” of microglia, including YM1 and arginase 1. The protein expression profile in the hippocampus demonstrated markedly increased levels of IL-6, GM-CSF and eotaxin (CCL-11) in response to CCL2, but no changes in the levels of other cytokines, including TNF-α and IFN-γ. Moreover, real-time PCR analysis confirmed increases in mRNA levels of gene transcripts associated with neuroinflammation following CCL2 overexpression. Finally, we investigated the chemotactic properties of CCL2 in vivo by performing adoptive transfer of bone marrow–derived cells (BMDCs) isolated from donor mice that ubiquitously expressed green fluorescent protein. Flow cytometry and histological analyses indicated that BMDCs extravasated into brain parenchyma and colabeled with microglial markers.

Conclusion

Taken together, our results suggest that CCL2 strongly activates resident microglia in the brain. Both pro- and anti-inflammatory activation of microglia were prominent, with no bias toward the M1 or M2 phenotype in the activated cells. As expected, CCL2 overexpression actively recruited circulating monocytes into the CNS. Thus, CCL2 expression in mouse brain induces microglial activation and represents an efficient method for recruitment of peripheral macrophages.

HMGB1 levels are increased in patients with juvenile idiopathic arthritis, correlate with early onset of disease, and are independent of disease duration

OBJECTIVE

High mobility group box chromosomal protein 1 (HMGB1) has been implicated as a mediator of inflammation in rheumatoid arthritis (RA), while its role in juvenile idiopathic arthritis (JIA) has not been described. To evaluate the role of HMGB1 in the inflammatory process in JIA and its potential as a therapeutic target, we investigated whether extracellular HMGB1 is detectable in JIA and if so, to correlate the levels with established inflammatory markers and clinical measures.

METHODS

Matching samples of blood and synovial fluid (SF) were collected from 23 patients with JIA. Levels of HMGB1, soluble receptor for advanced glycation endproducts, S100A12, myeloid-related protein 8/14, and other inflammatory mediators were analyzed.

RESULTS

Significantly increased HMGB1 levels were recorded in SF compared to blood samples from patients with JIA. The amount of HMGB1 was highest in patients with early disease onset irrespective of disease duration. In contrast, the proinflammatory S100 protein and interleukin 8 were highest in patients in early phases of disease. Matrix metalloproteinase-3, a marker of cartilage destruction, was higher in patients with late disease onset, indicating similarities with RA in that patient subgroup.

CONCLUSION

Levels of extracellular HMGB1 are increased in the inflamed joints of patients with JIA. This warrants further studies of HMGB1 as a mediator of JIA pathogenesis as well as a biomarker for inflammatory activity and as a target for therapy. The variation in levels of HMGB1 and S100 proteins in relation to disease onset indicates a difference in inflammatory phenotype during disease progression.

Increased expression of S100A8 and S100A9 in patients with diffuse cutaneous systemic sclerosis. A correlation with organ involvement and immunological abnormalities

S100A8 and S100A9 play important roles in immune and inflammatory disorders. The role of the two proteins in systemic sclerosis (SSc) remains unknown. Fifty-seven diffuse cutaneous SSc (dcSSc) patients, 31 limited cutaneous SSc (lcSSc) patients were recruited in the present study. The expression of S100A8 and S100A9 in plasma was measured using an enzyme-linked immunosorbent assay and the mRNA levels in peripheral blood were assessed using reverse transcriptase quantitative PCR. The expression and distribution of S100A8, S100A9, and receptor for advanced glycation end products (RAGE), in skin tissues was analyzed by immunohistochemistry. The plasma concentrations of S100A8 and S100A9 were significantly higher in dcSSc patients than in normal controls and lcSSc patients. Both S100A8 and S100A9 levels were significantly increased in dcSSc patients with lung or kidney involvement. Increased plasma levels of S100A8 and S100A9 in dcSSc patients were associated with several autoantibodies. Transcription levels of S100A8 and S100A9 in peripheral blood were found elevated in both dcSSc and lcSSc patients than normal controls. Immunohistochemistry demonstrated higher S100A8 and S100A9 expression in sclerotic skin than in normal skin. The number of S100A8, S100A9, or RAGE positive fibroblasts was also significantly increased. Highly elevated expression of both S100A8 and S100A9 was found in dcSSc patients. There was close correlation with disease severity and serological abnormalities, suggesting that the two proteins may play important roles in the development of systemic sclerosis.

ATG4B/autophagin-1 regulates intestinal homeostasis and protects mice from experimental colitis

The identification of inflammatory bowel disease (IBD) susceptibility genes by genome-wide association has linked this pathology to autophagy, a lysosomal degradation pathway that is crucial for cell and tissue homeostasis. Here, we describe autophagy-related 4B, cysteine peptidase/autophagin-1 (ATG4B) as an essential protein in the control of inflammatory response during experimental colitis. In this pathological condition, ATG4B protein levels increase in parallel with the induction of autophagy. Moreover, ATG4B expression is significantly reduced in affected areas of the colon from IBD patients. Consistently, atg4b (-/-) mice present Paneth cell abnormalities, as well as an increased susceptibility to DSS-induced colitis. atg4b-deficient mice exhibit significant alterations in proinflammatory cytokines and mediators of the immune response to bacterial infections, which are reminiscent of those found in patients with Crohn disease or ulcerative colitis. Additionally, antibiotic treatments and bone marrow transplantation from wild-type mice reduced colitis in atg4b (-/-) mice. Taken together, these results provided additional evidence for the importance of autophagy in intestinal pathologies and describe ATG4B as a novel protective protein in inflammatory colitis. Finally, we propose that atg4b-null mice are a suitable model for in vivo studies aimed at testing new therapeutic strategies for intestinal diseases associated with autophagy deficiency.

S100A12 suppresses pro-inflammatory, but not pro-thrombotic functions of serum amyloid A

S100A12 is elevated in the circulation in patients with chronic inflammatory diseases and recent studies indicate pleiotropic functions. Serum amyloid A induces monocyte cytokines and tissue factor. S100A12 did not stimulate IL-6, IL-8, IL-1β or TNF-α production by human peripheral blood mononuclear cells but low amounts consistently reduced cytokine mRNA and protein levels induced by serum amyloid A, by ∼49% and ∼46%, respectively. However, S100A12 did not affect serum amyloid A-induced monocyte tissue factor. In marked contrast, LPS-induced cytokines or tissue factor were not suppressed by S100A12. S100A12 did not alter cytokine mRNA stability or the cytokine secretory pathway. S100A12 and serum amyloid A did not appear to form complexes and although they may have common receptors, suppression was unlikely via receptor competition. Serum amyloid A induces cytokines via activation of NF-κB and the MAPK pathways. S100A12 reduced serum amyloid A-, but not LPS-induced ERK1/2 phosphorylation to baseline. It did not affect JNK or p38 phosphorylation or the NF-κB pathway. Reduction in ERK1/2 phosphorylation by S100A12 was unlikely due to changes in intracellular reactive oxygen species, Ca²⁺ flux or to recruitment of phosphatases. We suggest that S100A12 may modulate sterile inflammation by blunting pro-inflammatory properties of lipid-poor serum amyloid A deposited in chronic lesions where both proteins are elevated as a consequence of macrophage activation.

Human S100A9 protein is stabilized by inflammatory stimuli via the formation of proteolytically-resistant homodimers

S100A8 and S100A9 are Ca(2+)-binding proteins that are associated with acute and chronic inflammation and cancer. They form predominantly heterodimers even if there are data supporting homodimer formation. We investigated the stability of the heterodimer in myeloid and S100A8/S100A9 over-expressing COS cells. In both cases, S100A8 and S100A9 proteins were not completely degraded even 48 hrs after blocking protein synthesis. In contrast, in single transfected cells, S100A8 protein was completely degraded after 24 h, while S100A9 was completely unstable. However, S100A9 protein expression was rescued upon S100A8 co-expression or inhibition of proteasomal activity. Furthermore, S100A9, but not S100A8, could be stabilized by LPS, IL-1β and TNFα treatment. Interestingly, stimulation of S100A9-transfected COS cells with proteasomal inhibitor or IL-1β lead to the formation of protease resistant S100A9 homodimers. In summary, our data indicated that S100A9 protein is extremely unstable but can be rescued upon co-expression with S100A8 protein or inflammatory stimuli, via proteolytically resistant homodimer formation. The formation of S100A9 homodimers by this mechanism may constitute an amplification step during an inflammatory reaction.

Measurement of calprotectin in ascitic fluid to identify elevated polymorphonuclear cell count

AIM: To evaluate the diagnostic capability of calprotectin in ascitic fluid for detecting a polymorphonuclear (PMN) cell count > 250/μL ascites.

METHODS: In this prospective observational study, a total of 130 ascites samples were analysed from 71 consecutive patients referred for paracentesis. Total and differential leukocyte cell counts were determined manually with a Neubauer chamber and gentian-violet stain. Calprotectin was measured in 1 mL ascetic fluid by enzyme-linked immunosorbent assay (ELISA) and a point-of-care (POC) lateral flow assay with the Quantum Blue^® Reader (Bühlmann Laboratories). All measurements were carried out in a central laboratory by senior personnel blinded to patient history. A PMN count > 250/μL was the primary endpoint of the study. The diagnostic value of ascitic calprotectin measurement was assessed by comparing to the final diagnosis of each patient that had been adjudicated by investigators blinded to calprotectin values.

RESULTS: The PMN count was > 250/μL in 19 samples (14.6%) from 15 patients (21.1%) and varied widely among the study population (range 10-19 800/mL and 1-17 820/mL, respectively). Spontaneous bacterial peritonitis (SBP) was the final diagnosis in four patients (5.6%). All patients with PMN ≤ 250/μL had negative bacterial culture. PMN count was elevated in five patients with peritoneal carcinomatosis, three with lymphoma, one with neuroendocrine carcinoma, and two with secondary peritonitis due to abdominal perforation. PMN cell counts correlated with ascitic calprotectin values (Spearman’s rho; r = 0.457 for ELISA, r = 0.473 for POC). A considerable range of ascitic calprotectin concentrations was detected by ELISA [median 0.43 μg/mL, interquartile range (IQR) 0.23-1.23 (range 0.10-14.93)] and POC [median 0.38 μg/mL, IQR 0.38-0.56 (range 0.38-13.31)]. Ascitic calprotectin levels were higher in samples with PMN > 250/μL, by both ELISA [median (IQR) 2.48 μg/mL (1.61-3.65) vs 0.10 μg/mL (0.10-0.36), P < 0.001] and POC [2.78 μg/mL (2.05-5.37) vs 0.38 μg/mL (0.38-0.41), P < 0.001]. The area under the receiver operating characteristics curve for identifying an elevated PMN count was 0.977 (95%CI: 0.933 to 0.995) for ELISA and 0.982 (95%CI: 0.942 to 0.997) for POC (P = 0.246 vs ELISA). Using the optimal cut-off value for ELISA (0.63 μg/mL), ascitic calprotectin had 94.8% sensitivity, 89.2% specificity, positive and negative likelihood ratios of 8.76 and 0.06 respectively, positive and negative predictive values of 60.0% and 99.0% respectively, and 90.0% overall accuracy. Using the optimal cut-off value for POC (0.51 μg/mL), the respective values were 100.0%, 84.7%, 6.53, 0.00, 52.8%, 100% and 87.7%. Correlation between ELISA and POC was excellent (r = 0.873, P < 0.001). The mean ± SD of the difference was -0.11 ± 0.48 μg/mL with limits of agreement of + 0.8 μg/mL (95%CI: 0.69 to 0.98) and -1.1 μg/mL (95%CI: -1.19 to -0.91).

CONCLUSION: Ascitic calprotectin reliably predicts PMN count > 250/μL, which may prove useful in the diagnosis of SBP, especially with a readily available bedside testing device.

Identification of proteins from interstitium of trapezius muscle in women with chronic myalgia using microdialysis in combination with proteomics

Background

Microdialysis (MD) of the trapezius muscle has been an attractive technique to investigating small molecules and metabolites in chronic musculoskeletal pain in human. Large biomolecules such as proteins also cross the dialysis membrane of the catheters. In this study we have applied in vivo MD in combination with two dimensional gel electrophoresis (2-DE) and mass spectrometry to identify proteins in the extracellular fluid of the trapezius muscle.

Materials and Methods

Dialysate from women with chronic trapezius myalgia (TM; n = 37), women with chronic wide spread pain (CWP; n = 18) and healthy controls (CON; n = 22) was collected from the trapezius muscle using a catheter with a cut-off point of 100 kDa. Proteins were separated by two-dimensional gel electrophoresis and visualized by silver staining. Detected proteins were identified by nano liquid chromatography in combination with tandem mass spectrometry.

Results

Ninety-seven protein spots were identified from the interstitial fluid of the trapezius muscle; 48 proteins in TM and 30 proteins in CWP had concentrations at least two-fold higher or lower than in CON. The identified proteins pertain to several functional classes, e.g., proteins involved in inflammatory responses. Several of the identified proteins are known to be involved in processes of pain such as: creatine kinase, nerve growth factor, carbonic anhydrase, myoglobin, fatty acid binding protein and actin aortic smooth muscle.

Conclusions

In this study, by using in vivo microdialysis in combination with proteomics a large number of proteins in muscle interstitium have been identified. Several of the identified proteins were at least two-fold higher or lower in chronic pain patients. The applied techniques open up for the possibility of investigating protein changes associated with nociceptive processes of chronic myalgia.

Targeting the association of calgranulin B (S100A9) with insulin resistance and type 2 diabetes

Calgranulin B (S100A9) was recognized as a candidate type 2 diabetes (T2D) gene in the genomic profiling of muscle from a rodent model of T2D and identifying the human orthologs of genes localized in T2D susceptibility regions. Circulating and S100A9 expressions in muscle and adipose tissue, isolated fat cells, and mouse models were evaluated. A common 5'-upstream single-nucleotide polymorphism (SNP; rs3014866) for S100A9 was analyzed, as well as the effects of weight loss and treatments in vitro with recombinant S100A9. S100a9 expression was increased in muscle of diabetic mice (1.6-fold, p = 0.002), and in muscle from subjects with impaired glucose tolerance (∼4-fold, p = 0.028; n = 34). The rs3014866 SNP was associated with circulating S100A9 and the risk of T2D, having TT carriers at 28 % (p = 0.03) lower risk (n = 1,450). Indeed, increased circulating S100A9 (∼4-fold, p = 0.03; n = 206) and subcutaneous (2-fold, p = 0.01) and omental (1.4-fold, p = 0.04) S100A9 gene expressions (n = 83) in TT carriers run in parallel to decreased fasting glucose and glycated hemoglobin. Accordingly, metformin led to increased S100A9 mRNA in ex vivo-treated adipose tissue explants (n = 5/treatment). Otherwise, obese subjects showed a compensatory increase in circulating and S100A9 expressions in adipose (n = 126), as further demonstrated by decreased levels after diet- (-34 %, p = 0.002; n = 20) and surgery-induced (-58 %, p = 0.02; n = 8) weight loss. Lipopolysaccharide led to increased S100A9 in adipose from mice (n = 5/treatment) while recombinant S100A9 downregulated inflammation in adipocytes (n = 3/treatment). Current findings support the strategy of testing differentially expressed genes in mice and human orthologs associated with T2D. The increased S100A9 reported for obesity and insulin resistance may be envisioned as a compensatory mechanism for inflammation.

Induction of nuclear factor-κB responses by the S100A9 protein is Toll-like receptor-4-dependent

Interactions between danger-associated molecular patterns (DAMP) and pathogen-associated molecular patterns (PAMP) and pattern recognition receptors such as Toll-like receptors (TLRs) are critical for the regulation of the inflammatory process via activation of nuclear factor-κB (NF-κB) and cytokine secretion. In this report, we investigated the capacity of lipopolysaccharide (LPS) -free S100A9 (DAMP) protein to activate human and mouse cells compared with lipoprotein-free LPS (PAMP). First, we showed that LPS and S100A9 were able to increase NF-κB activity followed by increased cytokine and nitric oxide (NO) secretion both in human THP-1 cells and in mouse bone marrow-derived dendritic cells. Surprisingly, although S100A9 triggered a weaker cytokine response than LPS, we found that S100A9 more potently induced IκBα degradation and hence NF-κB activation. Both the S100A9-induced response and the LPS-induced response were completely absent in TLR4 knockout mice, whereas it was only slightly affected in RAGE knockout mice. Also, we showed that LPS and S100A9 NF-κB induction were strongly reduced in the presence of specific inhibitors of TLR-signalling. Chloroquine reduced S100A9 but not LPS signalling, indicating that S100A9 may need to be internalized to be fully active as a TLR4 inducer. This was confirmed using A488-labelled S100A9 that was internalized in THP-1 cells, showing a raise in fluorescence after 30 min at 37°. Chloroquine treatment significantly reduced the fluorescence. In summary, our data indicate that both human and mouse S100A9 are TLR4 agonists. Importantly, S100A9 induced stronger NF-κB activation albeit weaker cytokine secretion than LPS, suggesting that S100A9 and LPS activated NF-κB in a qualitatively distinct manner.

The elevated serum S100A8/A9 during acute myocardial infarction is not of cardiac myocyte origin

Overproduction of circulating S100A8/A9 occurs in patients following acute myocardial infarction (AMI). It remains unclear whether ischemia insult per se induces S100A8 and S100A9 expression in cardiac myocytes or even whether the cardiac myocytes participate as a source of these proteins. In this study, western blot analysis and quantitative real-time reverse transcription polymerase chain reaction were used to test samples obtained from isolated spontaneously hypertensive rat hearts and Wistar-Kyoto rat hearts subjected to global normothermic ischemia and from neonatal Wistar rat cardiac myocytes undergoing hypoxia. Ischemia did not increase the expression of S100A8 and S100A9 proteins and mRNA in the myocardium either from the spontaneously hypertensive rat hearts or the Wistar-Kyoto rat hearts. In addition, the levels of S100A8 and S100A9 proteins were unchanged in the neonatal rat cardiac myocytes undergoing hypoxia. However, both ischemia and hypoxia activated NF-kappaB in ischemic myocardium and in hypoxic cardiac cells in a time-dependent manner. The results suggest that the increased serum S100A8/A9 concentrations following AMI were not of cardiac myocyte origin.

Receptor for advanced glycation end products (RAGE) and implications for the pathophysiology of heart failure

The receptor for advanced glycation end products (RAGE) is expressed in the heart in cardiomyocytes, vascular cells, fibroblasts, and in infiltrating inflammatory cells. Experiments in murine, rat, and swine models of injury suggest that RAGE and the ligands of RAGE are upregulated in key injuries to the heart, including ischemia/reperfusion injury, diabetes, and inflammation. Pharmacological antagonism of RAGE or genetic deletion of the receptor in mice is strikingly protective in models of these stresses. Data emerging from human studies suggest that measurement of levels of RAGE ligands or soluble RAGEs in plasma or serum may correlate with the degree of heart failure. Taken together, the ligand-RAGE axis is implicated in heart failure and we predict that therapeutic antagonism of RAGE might be a unique target for therapeutic intervention in this disorder.

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.

Serum S100A8/A9, But Not Follistatin-like Protein 1 and Interleukin 18, May Be a Useful Biomarker of Disease Activity in Adult-onset Still’s Disease

Objective.

S100A8/A9, follistatin-like protein 1, and interleukin 18 (IL-18) have been suggested as biomarkers of disease activity in patients with systemic juvenile idiopathic arthritis or adult-onset Still’s disease (AOSD). We investigated the clinical significance of these factors in AOSD.

Methods.

Blood samples were collected from 36 patients with AOSD, 40 patients with rheumatoid arthritis (RA), and 33 healthy controls. Of the patients with AOSD, followup samples were collected from 16 patients after resolution of disease activity.

Results.

Serum levels of S100A8/A9 (11.77 ± 8.84 μg/ml) in AOSD patients were higher than those in RA patients (3.53 ± 3.43 μg/ml; p < 0.001) and controls (2.49 ± 1.83 μg/ml; p < 0.001). Follistatin-like protein 1 levels in AOSD were not different from those in RA and controls. IL-18 levels in AOSD (7560.3 ± 7577.6 pg/ml) were higher than those in RA (217.7 ± 292.1 pg/ml; p < 0.001) and controls (139.2 ± 86.2 pg/ml; p < 0.001). The sensitivity and specificity of IL-18 for diagnosing AOSD was highest with a cutoff value of 366.1 pg/ml. Serum S100A8/A9 correlated with leukocyte count, erythrocyte sedimentation rate, C-reactive protein, ferritin, and systemic disease score; however, IL-18 correlated only with ferritin and systemic disease score. S100A8/A9 was decreased after disease activity was resolved in followup of AOSD patients (9.96 ± 7.35 μg/ml in active AOSD vs 3.6 ± 4.77 μg/ml in resolved cases; p = 0.001). The change of S100A8/A9 was well correlated with that of systemic disease score.

Conclusion.

The data suggest that serum S100A8/A9 may be a useful biomarker for evaluating disease activity in patients with AOSD.

Circulating DNA and myeloperoxidase indicate disease activity in patients with thrombotic microangiopathies

Thrombotic microangiopathies (TMAs) are a group of life-threatening disorders characterized by thrombocytopenia, fragmentation of erythrocytes, and ischemic organ damage. Genetic disorders, autoimmune disease, and cancer are risk factors for TMAs, but an additional, unknown trigger is needed to bring about acute disease. Recent studies suggest that DNA and histones are released during inflammation or infection and stimulate coagulation, thrombosis, thrombocytopenia, and organ damage in mice. We show that extracellular DNA and histones as well as markers of neutrophils are present in acute TMAs. Analysis of plasma from TMA patients of different clinical categories revealed elevated levels of DNA-histone complexes and myeloperoxidase (MPO) from neutrophil granules as well as S100A8/A9, a heterocomplex abundant in neutrophil cytosol. During therapy of thrombotic thrombocytopenic purpura, a subtype of TMAs often associated with severe ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motifs, member 13) deficiency, plasma DNA and MPO were inversely correlated with platelet counts, and their levels indicated amelioration or exacerbation of the disease. ADAMTS13 deficiency together with increased levels of plasma DNA and MPO were characteristic for acute thrombotic thrombocytopenic purpura. A minor infection often precedes acute TMA and extracellular DNA and histones released during the inflammatory response could provide the second hit, which precipitates acute TMA in patients with pre-existing risk factors.

High Levels of S100A12 Are Associated With Recent Plaque Symptomatology in Patients With Carotid Atherosclerosis

Background and Purpose—

Atherosclerosis is a progressive chronic disease, in which inflammation plays a key role. The calcium-binding proteins calgranulins including S100A8, S100A9, and S100A12 are involved in many cellular activities and pathological processes including inflammation. We therefore hypothesized that calgranulins may be markers of plaque instability in patients with carotid atherosclerosis.

Methods—

Plasma levels of S100A8/A9 and S100A10 were measured in 159 consecutive patients with high-grade carotid stenosis and in 22 healthy control subjects. The mRNA levels of calgranulins were also measured within the atherosclerotic carotid plaques, and their regulation was analyzed in vitro in monocytes.

Results—

Our main findings were: (1) plasma levels of S100A12 were significantly higher in patients with carotid atherosclerosis compared with healthy control subjects with the highest levels in patients with the most recent symptoms (ie, within 2 months); (2) plasma levels of S100A8/S100A9 showed a modest increase in patients with symptoms in the previous 2 to 6 months but not in the other patients; (3) mRNA levels of S100A8, S100A9, and S100A12 showed increased expression in atherosclerotic carotid plaques from patients with the most recent symptoms compared with the remaining patients; (4) in THP-1 monocytes, activation of Toll-like receptors 2 and 4 increased mRNA levels of S100A8, S100A9, and S10012 and interleukin-1β, interferon γ, and releasate from thrombin-activated platelets significantly enhanced the expression of S100A12.

Conclusions—

Our findings support a link between calgranulins and atherogenesis and suggest that these mediators, and in particular S100A12, may be related to plaque instability.

EN-RAGE (extracellular newly identified receptor for advanced glycation end-products binding protein) and mortality of long-term hemodialysis patients: A prospective observational cohort study

OBJECTIVES

EN-RAGE is extracellular newly identified receptor for advanced glycation end-products binding protein playing a role in inflammation. The aim was to test the relationship of EN-RAGE to prognosis of long-term hemodialysis patients (HD).

DESIGN AND METHODS

This is a prospective observational cohort study in 261 HD patients followed up for five years. Laboratory parameters were measured at the beginning of the study.

RESULTS

EN-RAGE was slightly but unsignificantly increased in HD patients compared with healthy controls and correlated significantly with inflammatory markers. Univariate Cox analysis demonstrated EN-RAGE as a significant predictor for mortality due to infection (HR (95%CI): 1.305 (1.063-1.602), per standard deviation, p=0.01), but this significance disappeared in multivariate Cox analysis when CRP was included into the model.

CONCLUSIONS

Our study demonstrates EN-RAGE as an inflammatory biomarker. It is related to mortality of HD patients due to infection, but in our study, it did not provide additional information to CRP.

C-reactive Protein Is a More Sensitive and Specific Marker for Diagnosing Bacterial Infections in Systemic Lupus Erythematosus Compared to S100A8/A9 and Procalcitonin

Objective.

C-reactive protein (CRP), S100A8/A9, and procalcitonin have been suggested as markers of infection in patients with systemic lupus erythematosus (SLE). We investigated the clinical significance of these factors for indication of infection in SLE.

Methods.

Blood samples were prospectively collected from 34 patients with SLE who had bacterial infections and 39 patients with SLE who had disease flares and no evidence of infection. A second set of serum samples was collected after the infections or flares were resolved.

Results.

CRP levels of SLE patients with infections were higher than those with flares [5.9 mg/dl (IQR 2.42, 10.53) vs 0.06 mg/dl (IQR 0.03, 0.15), p < 0.001] and decreased after the infection was resolved. S100A8/A9 and procalcitonin levels of SLE patients with infection were also higher [4.69 μg/ml (IQR 2.25, 12.07) vs 1.07 (IQR 0.49, 3.05) (p < 0.001) and 0 ng/ml (IQR 0–0.38) vs 0 (0–0) (p < 0.001), respectively]; these levels were also reduced once the infection disappeared. In the receiver-operating characteristics analysis of CRP, S100A8/A9, and procalcitonin, the area under the curve was 0.966 (95% CI 0.925–1.007), 0.732 (95% CI 0.61–0.854), and 0.667 (95% CI 0.534–0.799), respectively. CRP indicated the presence of an infection with a sensitivity of 100% and a specificity of 90%, with a cutoff value of 1.35 mg/dl.

Conclusion.

Our data suggest that CRP is the most sensitive and specific marker for diagnosing bacterial infections in SLE.

Transcription analysis on response of porcine alveolar macrophages to Haemophilus parasuis

Background

Haemophilus parasuis (H. parasuis) is the etiological agent of Glässer's disease in pigs. Currently, the molecular basis of this infection is largely unknown. The innate immune response is the first line of defense against the infectious disease. Systematical analysis on host innate immune response to the infection is important for understanding the pathogenesis of the infectious microorganisms.

Results

A total of 428 differentially expressed (DE) genes were identified in the porcine alveolar macrophages (PAMs) 6 days after H. parasuis infection. These genes were principally related to inflammatory response, immune response, microtubule polymerization, regulation of transcript and signal transduction. Through the pathway analysis, the significant pathways mainly concerned with cell adhesion molecules, cytokine-cytokine receptor interaction, complement and coagulation cascades, toll-like receptor signaling pathway, MAPK signaling pathway, suggesting that the host took different strategies to activate immune and inflammatory response upon H. parasuis infection. The global interactions network and two subnetworks of the proteins encoded by DE genes were analyzed by using STRING. Further immunostimulation analysis indicated that mRNA levels of S100 calcium-binding protein A4 (S100A4) and S100 calcium-binding protein A6 (S100A6) in porcine PK-15 cells increased within 48 h and were sustained after administration of lipopolysaccharide (LPS) and Poly (I:C) respectively. The s100a4 and s100a6 genes were found to be up-regulated significantly in lungs, spleen and lymph nodes in H. parasuis infected pigs. We firstly cloned and sequenced the porcine coronin1a gene. Phylogenetic analysis showed that poCORONIN 1A belonged to the group containing the Bos taurus sequence. Structural analysis indicated that the poCORONIN 1A contained putative domains of Trp-Asp (WD) repeats signature, Trp-Asp (WD) repeats profile and Trp-Asp (WD) repeats circular profile at the N-terminus.

Conclusions

Our present study is the first one focusing on the response of porcine alveolar macrophages to H. parasuis. Our data demonstrate a series of genes are activated upon H. parasuis infection. The observed gene expression profile could help screening the potential host agents for reducing the prevalence of H. parasuis and further understanding the molecular pathogenesis associated with H. parasuis infection in pigs.