Pro-inflammatory S100A8 and S100A9 proteins: self-assembly into multifunctional native and amyloid complexes

Transcriptomic stratification of late-onset Alzheimer's cases reveals novel genetic modifiers of disease pathology

Late-Onset Alzheimer's disease (LOAD) is a common, complex genetic disorder well-known for its heterogeneous pathology. The genetic heterogeneity underlying common, complex diseases poses a major challenge for targeted therapies and the identification of novel disease-associated variants. Case-control approaches are often limited to examining a specific outcome in a group of heterogenous patients with different clinical characteristics. Here, we developed a novel approach to define relevant transcriptomic endophenotypes and stratify decedents based on molecular profiles in three independent human LOAD cohorts. By integrating post-mortem brain gene co-expression data from 2114 human samples with LOAD, we developed a novel quantitative, composite phenotype that can better account for the heterogeneity in genetic architecture underlying the disease. We used iterative weighted gene co-expression network analysis (WGCNA) to reduce data dimensionality and to isolate gene sets that are highly co-expressed within disease subtypes and represent specific molecular pathways. We then performed single variant association testing using whole genome-sequencing data for the novel composite phenotype in order to identify genetic loci that contribute to disease heterogeneity. Distinct LOAD subtypes were identified for all three study cohorts (two in ROSMAP, three in Mayo Clinic, and two in Mount Sinai Brain Bank). Single variant association analysis identified a genome-wide significant variant in TMEM106B (p-value < 5×10-8, rs1990620G) in the ROSMAP cohort that confers protection from the inflammatory LOAD subtype. Taken together, our novel approach can be used to stratify LOAD into distinct molecular subtypes based on affected disease pathways.

Serum alarmin S100A8/S100A9 levels and its potential role as biomarker in myocarditis

Aims

The alarmin S100A8/S100A9 (S100A8/A9) is released by activated monocytes/macrophages and neutrophils in the setting lymphocytic myocarditis (MC). We recently demonstrated its therapeutic potential in experimental acute MC. Now, we investigated the diagnostic relevance of S100A8/A9 serum levels in patients with suspected acute and chronic MC and in patients with heart failure without cardiac inflammation.

Methods and Results

Serum S100A8/A9 levels were analysed in patients with a recent onset of MC [≤ 30 days, n = 32; ejection fraction (EF): 45.4 ± 12.9%], dilated cardiomyopathy patients with inflammation (n = 112; EF: 29.0 ± 11.4%), or without inflammation (n = 58; EF: 26.6 ± 9.3%), and controls (n = 25; EF: 68.5 ± 4.6%), by using specific ELISAs. Blood samples were collected at Time Point 1 (T1), where also endomyocardial biopsies (EMBs) were withdrawn. Patients with a recent onset of MC showed a 4.6‐fold increase in serum S100A8/A9 levels vs. controls (MC: 1948 ± 1670 ng/mL vs. controls: 426 ± 307 ng/mL; P < 0.0001). Serum S100A8/A9 correlated with the disease activity, represented by EMB‐derived counts of inflammatory cells (CD3: r = 0.486, P = 0.0047, lymphocyte function‐associated antigen‐1: r = 0.558, P = 0.0009, macrophage‐1 antigen: r = 0.434, P = 0.013), the EMB mRNA levels of S100A8, S100A9 (r = 0.541, P = 0.002), and left ventricular ejection fraction (LVEF: r = 0.498, P = 0.0043). EMB immunofluorescence co‐stainings display macrophages/monocytes and neutrophils as the main source of S100A8 and S100A9 in recent onset MC. The diagnostic value of serum alarmin levels (cut‐off 583 ng/mL) was characterized by a specificity of 92%, a sensitivity of 90.6%, positive predictive value of 93.5%, negative predictive value of 88.5%, and an accuracy of 0.949 (95% confidence interval [0.89–1]). In a subgroup of MC patients, S100A8/A9 serum levels and EMBs at T1 (n = 12) and a follow‐up visit (T2, n = 12, mean follow‐up 8.5 months) were available. A fall of serum S100A8/A9 (T1: 2208 ± 1843 ng/mL vs. T2: 888.8 ± 513.7 ng/mL; P = 0.00052) was associated with a reduced cardiac inflammation (CD3 T1: 70.02 ± 107.4 cells per square millimetre vs. T2: 59.18 ± 182.5 cells per square millimetre; P = 0.0342, lymphocyte function‐associated antigen‐1 T1: 133.5 ± 187.1 cells per square millimetre vs. T2: 74.12 ± 190.5 cells per square millimetre; P = 0.0186, and macrophage‐1 antigen T1: 132.6 ± 129.5 cells per square millimetre vs. T2: 54.41 ± 65.16 cells per square millimetre; P = 0.0015). Serum S100A8/A9 levels were only slightly increased in patients within the chronic phase of MC and in heart failure patients without inflammation vs. controls.

Conclusions

Serum S100A8/A9 might serve as an additional tool in the diagnostic workup of suspected acute MC patients.

S100-Alarmins Are Essential Pilots of Postnatal Innate Immune Adaptation

The restricted capacity of newborn infants to mount inflammatory responses toward microbial challenges has traditionally been linked to the high risk of septic diseases during the neonatal period. In recent years, substantial evidence has been provided that this characteristic of the neonatal immune system is actually a meaningful physiologic state that is based on specific transiently active cellular and molecular mechanisms and required for a favorable course of postnatal immune adaptation. The identification of physiologically high amounts of S100-alarmins in neonates has been one of the crucial pieces in the puzzle that contributed to the change of concept. In this context, innate immune immaturity could be redefined and assigned to the epigenetic silence of adult-like cell-autonomous regulation at the beginning of life. S100-alarmins represent an alternative age-specific mechanism of immune regulation that protects neonates from hyperinflammatory immune responses. Here, we summarize how infants are provided with S100-alarmins and why these allow an uneventful clash between the innate immune system and the extrauterine world. The mode of action of S100-alarmins is highlighted including their tuning functions at multiple levels for establishing a state of homeostasis with the environment in the newborn individual.

Evolution of multifunctionality through a pleiotropic substitution in the innate immune protein S100A9

Multifunctional proteins are evolutionary puzzles: how do proteins evolve to satisfy multiple functional constraints? S100A9 is one such multifunctional protein. It potently amplifies inflammation via Toll-like receptor four and is antimicrobial as part of a heterocomplex with S100A8. These two functions are seemingly regulated by proteolysis: S100A9 is readily degraded, while S100A8/S100A9 is resistant. We take an evolutionary biochemical approach to show that S100A9 evolved both functions and lost proteolytic resistance from a weakly proinflammatory, proteolytically resistant amniote ancestor. We identify a historical substitution that has pleiotropic effects on S100A9 proinflammatory activity and proteolytic resistance but has little effect on S100A8/S100A9 antimicrobial activity. We thus propose that mammals evolved S100A8/S100A9 antimicrobial and S100A9 proinflammatory activities concomitantly with a proteolytic 'timer' to selectively regulate S100A9. This highlights how the same mutation can have pleiotropic effects on one functional state of a protein but not another, thus facilitating the evolution of multifunctionality.

S100 Soil Sensor Receptors and Molecular Targeting Therapy Against Them in Cancer Metastasis

The molecular mechanisms underlying the ‘seed and soil’ theory are unknown. S100A8/A9 (a heterodimer complex of S100A8 and S100A9 proteins that exhibits a ‘soil signal’) is a ligand for Toll-like receptor 4, causing distant melanoma cells to approach the lung as a ‘seeding’ site. Unknown soil sensors for S100A8/A9 may exist, e.g., extracellular matrix metalloproteinase inducer, neuroplastin, activated leukocyte cell adhesion molecule, and melanoma cell adhesion molecule. We call these receptor proteins ‘novel S100 soil sensor receptors (novel SSSRs).’ Here we review and summarize a crucial role of the S100A8/A9-novel SSSRs' axis in cancer metastasis. The binding of S100A8/A9 to individual SSSRs is important in cancer metastasis via upregulations of the epithelial-mesenchymal transition, cellular motility, and cancer cell invasiveness, plus the formation of an inflammatory immune suppressive environment in metastatic organ(s). These metastatic cellular events are caused by the SSSR-featured signal transductions we identified that provide cancer cells a driving force for metastasis. To deprive cancer cells of these metastatic forces, we developed novel biologics that prevent the interaction of S100A8/A9 with SSSRs, followed by the efficient suppression of S100A8/A9-mediated lung-tropic metastasis in vivo.

Calprotectin (S100A8/S100A9)-induced cytotoxicity and apoptosis in human gastric cancer AGS cells: Alteration in expression levels of Bax, Bcl-2, and ERK2

Calprotectin is a heterodimeric EF-hand Ca²⁺ binding protein that is typically released by infiltrating polymorphonuclear leukocytes and macrophages. This protein is a key player linking inflammation and cancer. Due to the increased levels of calprotectin in different inflammatory diseases and cancer, it is considered as a marker for diagnostic purposes. In this study, we evaluated the mechanism of cell viability and apoptotic-inducing effects of recombinant human calprotectin (rhS100A8/S100A9) on the gastric adenocarcinoma (AGS), the most common type of gastric cancer cell line. AGS cells were exposed to the different concentrations (5-100 μg/ml) of calprotectin for 24, 48, and 72 h, and cell viability was assessed through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptotic-inducing effects of calprotectin were evaluated by sub-G1 cell cycle assay and Annexin V/propidium iodide double staining. Furthermore, real-time polymerase chain reaction and Western blot analysis were performed to evaluate the mechanism of action of calprotectin. Our findings indicated that calprotectin inhibits growth and viability of AGS cells in a time- and dose-dependent manner. The half-maximal inhibitory concentration values were measured as 85.77, 79.14, and 65.39 μg/ml for 24, 48, and 72 h, respectively. Additionally, we found that calprotectin downregulated the expression of antiapoptotic protein Bcl-2 and upregulated proapoptotic protein Bax in a time- and concentration-dependent fashion. Calprotectin also slightly upregulated the expression of extracellular signal-regulated protein kinase 2 (ERK2), while it significantly decreased the levels of phospho-ERK in a time-dependent manner. Overall, these findings indicated that calprotectin has cytotoxicity and apoptosis-inducing effects on AGS cell lines in high concentration by modulating Bax/Bcl-2 expression ratio accompanied by inhibition of ERK activation.

S100A8/S100A9 deficiency increases neutrophil activation and protective immune responses against invading infective L3 larvae of the filarial nematode Litomosoides sigmodontis

Neutrophils are essentially involved in protective immune responses against invading infective larvae of filarial nematodes. The present study investigated the impact of S100A8/S100A9 on protective immune responses against the rodent filarial nematode Litomosoides sigmodontis. S100A9 forms with S100A8 the heterodimer calprotectin, which is expressed by circulating neutrophils and monocytes and mitigates or amplifies tissue damage as well as inflammation depending on the immune environment. Mice deficient for S100A8/A9 had a significantly reduced worm burden in comparison to wildtype (WT) animals 12 days after infection (dpi) with infective L3 larvae, either by the vector or subcutaneous inoculation, the latter suggesting that circumventing natural immune responses within the epidermis and dermis do not alter the phenotype. Nevertheless, upon intradermal injection of L3 larvae, increased total numbers of neutrophils, eosinophils and macrophages were observed within the skin of S100A8/A9-/- mice. Furthermore, upon infection the bronchoalveolar and thoracic cavity lavage of S100A8/A9-/- mice showed increased concentrations of CXCL-1, CXCL-2, CXCL-5, as well as elastase in comparison to the WT controls. Neutrophils from S100A8/A9-/- mice exhibited an increased in vitro activation and reduced L3 larval motility more effectively in vitro compared to WT neutrophils. The depletion of neutrophils from S100A8/A9-/- mice prior to L. sigmodontis infection until 5dpi abrogated the protective effect and led to an increased worm burden, indicating that neutrophils mediate enhanced protective immune responses against invading L3 larvae in S100A8/A9-/- mice. Interestingly, complete circumvention of protective immune responses in the skin and the lymphatics by intravenous injection of L3 larvae reversed the phenotype and resulted in an increased worm burden in S100A8/A9-/- mice. In summary, our results reveal that lack of S100A8/S100A9 triggers L3-induced inflammatory responses, increasing chemokine levels, granulocyte recruitment as well as neutrophil activation and therefore impairs larval migration and susceptibility for filarial infection.

Top-Down and Bottom-Up Proteomics of Circulating S100A8/S100A9 in Plasma of Septic Shock Patients

Well-characterized prognostic biomarkers and reliable quantitative methods are key in sepsis management. Among damage-associated molecular patterns, S100A8/S100A9 complexes are reported to be markers for injured cells and to improve the prediction of death in septic shock patients. In view of the structural diversity observed for the intracellular forms, insight into circulating complexes and proteoforms is required to establish prognostic biomarkers. Here, we developed top-down and bottom-up proteomics to characterize the association of S100A8 and S100A9 in complexes and major circulating proteoforms. An antibody-free method was developed for absolute quantification of S100A8/S100A9 in a cohort of 49 patients to evaluate the prognostic value on the first day after admission for septic shock. The predominant circulating forms identified by top-down proteomics were S100A8, mono-oxidized S100A8, truncated acetylated S100A9, and S-nitrosylated S100A9. S100A8, truncated acetylated S100A9, and mono-oxidized S100A8 discriminated between survivors and nonsurvivors, along with total S100A8/S100A9 measured by the antibody-free bottom-up method. Overall, new insights into circulating S100A8/S100A9 and confirmation of its prognostic value in septic shock are crucial in qualification of this biomarker. Also, the simple antibody-free assay would support the harmonization of S100A8/S100A9 measurements.

Pathological roles of MRP14 in anemia and splenomegaly during experimental visceral leishmaniasis

Myeloid-related protein 14 (MRP14) belongs to the S100 calcium-binding protein family and is expressed in neutrophils and inflammatory macrophages. Increase in the number of MRP14+ cells or serum level of MRP14 is associated with various diseases such as autoimmune diseases and infectious diseases, suggesting the involvement of the molecule in pathogenesis of those diseases. In this study, to examine the pathological involvement of MRP14 during cutaneous and visceral leishmaniasis, wild-type (WT) and MRP14 knockout (MRP14KO) mice were infected with Leishmania major and L. donovani. Increase in the number of MRP14+ cells at the infection sites in wild-type mice was commonly found in the skin during L. major infection as well as the spleen and liver during L. donovani infection. In contrast, the influence of MRP14 to the pathology seemed different between the two infections. MRP14 depletion exacerbated the lesion development and ulcer formation in L. major infection. On the other hand, the depletion improved anemia and splenomegaly but not hepatomegaly at 24 weeks of L. donovani infection. These results suggest that, distinct from its protective role in CL, MRP14 is involved in exacerbation of some symptoms during VL.

S100 Calcium-Binding Protein A9 Knockout Contributes to Neuroprotection and Functional Improvement after Traumatic Brain Injury

S100 calcium-binding protein A9 (S100a9), a proinflammatory protein, has been shown to be involved in the development of neuroinflammatory disorders and neurodegenerative diseases. Upregulation of S100a9 in the brain during acute brain injury has been proposed to be associated with acute neuroinflammation. However, it remains unclear whether eliminating S100a9 expression will show beneficial outcomes after traumatic brain injury (TBI). Using S100a9 knockout mice, this study has demonstrated that S100a9 deletion ameliorates post-TBI anxiety, improves TBI-impaired motor and cognitive function, reduces lesion size, prevents perilesional neuron loss and neurodegeneration, diminishes neuroinflammation and TBI-induced neurogenesis, and enhances perilesional expression of neuroplasticity protein. These findings suggest that S100a9 plays a detrimental role in TBI. Genetic deletion of S100a9 enhances neuroprotection and improves functional outcome after TBI. This study sheds light on the pathological involvement of S100a9 in TBI, which would provide a new therapeutic target to minimize TBI-induced brain damage.

Effects of Iron Oxide Nanoparticles (γ-Fe2O3) on Liver, Lung and Brain Proteomes following Sub-Acute Intranasal Exposure: A New Toxicological Assessment in Rat Model Using iTRAQ-Based Quantitative Proteomics

Iron Oxide Nanoparticles (IONPs) present unique properties making them one of the most used NPs in the biomedical field. Nevertheless, for many years, growing production and use of IONPs are associated with risks that can affect human and the environment. Thus, it is essential to study the effects of these nanoparticles to better understand their mechanism of action and the molecular perturbations induced in the organism. In the present study, we investigated the toxicological effects of IONPs (γ-Fe2O3) on liver, lung and brain proteomes in Wistar rats. Exposed rats received IONP solution during 7 consecutive days by intranasal instillation at a dose of 10 mg/kg body weight. An iTRAQ-based quantitative proteomics was used to study proteomic variations at the level of the three organs. Using this proteomic approach, we identified 1565; 1135 and 1161 proteins respectively in the brain, liver and lung. Amon them, we quantified 1541; 1125 and 1128 proteins respectively in the brain, liver and lung. Several proteins were dysregulated comparing treated samples to controls, particularly, proteins involved in cytoskeleton remodeling, cellular metabolism, immune system stimulation, inflammation process, response to oxidative stress, angiogenesis, and neurodegenerative diseases.

In silico assessment of human Calprotectin subunits (S100A8/A9) in presence of sodium and calcium ions using Molecular Dynamics simulation approach

Calprotectin is a heterodimeric protein complex which consists of two subunits including S100A8 and S100A9. This protein has a major role in different inflammatory disease and various types of cancers. In current study we aimed to evaluate the structural and thermodynamic changes of the subunits and the complex in presence of sodium and calcium ions using molecular dynamics (MD) simulation. Therefore, the residue interaction network (RIN) was visualized in Cytoscape program. In next step, to measure the binding free energy, the potential of mean force (PMF) method was performed. Finally, the molecular mechanics Poisson-Boltzmann surface area (MMPBSA) method was applied as an effective tool to calculate the molecular model affinities. The MD simulation results of the subunits represented their structural changes in presence of Ca2+. Moreover, the RIN and Hydrogen bond analysis demonstrated that cluster interactions between Calprotectin subunits in presence of Ca2+ were greater in comparison with Na+. Our findings indicated that the binding free energy of the subunits in presence of Ca2+ was significantly greater than Na+. The results revealed that Ca2+ has the ability to induce structural changes in subunits in comparison with Na+ which lead to create stronger interactions between. Hence, studying the physical characteristics of the human proteins could be considered as a powerful tool in theranostics and drug design purposes.

The value of mRNA expression of S100A8 and S100A9 as blood-based biomarkers of inflammatory bowel disease

BACKGROUND AND STUDY AIMS

Non-invasive biomarkers of inflammatory bowel diseases (IBD) are of critical importance. Here, we evaluated the S100A8 and S100A9 mRNA expression, as the heterodimers of calprotectin, in the blood leucocytes of IBD patients to find how their expression associates with the disease characteristics.

PATIENTS AND METHODS

In this cross-sectional study, 59 IBD patients and 30 healthy subjects were included. The flare and remission phases of disease were identified in 46 and 13 patients, respectively. Blood leucocytes were isolated, and the S100A8 and S100A9 mRNA expression were evaluated in the isolated leucocytes using relative quantification real-time PCR.

RESULTS

The mean S100A8 and S100A9 mRNA expression were significantly higher in IBD patients than in the controls (p = 0.03 and p = 0.02, respectively). The mean S100A8 and S100A9 mRNA expression were significantly higher in the flare phase of the disease compared with the remission phase (p = 0.01 and p = 0.007, respectively). S100A8 distinguished IBD patients from controls with the sensitivity and specificity of 73% and 64%, and flare phase of disease from remission with the sensitivity and specificity of 67% and 62%. On the other hand, S100A9 distinguished IBD patients from controls with the sensitivity and specificity of 81% and 70%, and flare phase of disease from remission with the sensitivity and specificity of 68% and 64%.

CONCLUSION

The S100A8 and S100A9 mRNA are differentially expressed in blood leucocytes of IBD patients compared to healthy controls as well as active versus quiescent disease. Thus, they can be potentially used as a blood-based biomarker in the monitoring of IBD.

Emerging Alternative Proteinases in APP Metabolism and Alzheimer's Disease Pathogenesis: A Focus on MT1-MMP and MT5-MMP

Processing of amyloid beta precursor protein (APP) into amyloid-beta peptide (Aβ) by β-secretase and γ-secretase complex is at the heart of the pathogenesis of Alzheimer’s disease (AD). Targeting this proteolytic pathway effectively reduces/prevents pathology and cognitive decline in preclinical experimental models of the disease, but therapeutic strategies based on secretase activity modifying drugs have so far failed in clinical trials. Although this may raise some doubts on the relevance of β- and γ-secretases as targets, new APP-cleaving enzymes, including meprin-β, legumain (δ-secretase), rhomboid-like protein-4 (RHBDL4), caspases and membrane-type matrix metalloproteinases (MT-MMPs/η-secretases) have confirmed that APP processing remains a solid mechanism in AD pathophysiology. This review will discuss recent findings on the roles of all these proteinases in the nervous system, and in particular on the roles of MT-MMPs, which are at the crossroads of pathological events involving not only amyloidogenesis, but also inflammation and synaptic dysfunctions. Assessing the potential of these emerging proteinases in the Alzheimer’s field opens up new research prospects to improve our knowledge of fundamental mechanisms of the disease and help us establish new therapeutic strategies.

Human Immunodeficiency Virus (HIV) Infection and Use of Illicit Substances Promote Secretion of Semen Exosomes that Enhance Monocyte Adhesion and Induce Actin Reorganization and Chemotactic Migration

Semen exosomes (SE) from HIV-uninfected (HIV−) individuals potently inhibit HIV infection in vitro. However, morphological changes in target cells in response to SE have not been characterized or have the effect of HIV infection or the use of illicit substances, specifically psychostimulants, on the function of SE been elucidated. The objective of this study was to evaluate the effect of HIV infection, psychostimulant use, and both together on SE-mediated regulation of monocyte function. SE were isolated from semen of HIV− and HIV-infected (HIV+) antiretroviral therapy (ART)-naive participants who reported either using or not using psychostimulants. The SE samples were thus designated as HIV−Drug−, HIV−Drug+, HIV+Drug−, and HIV+Drug+. U937 monocytes were treated with different SEs and analyzed for changes in transcriptome, morphometrics, actin reorganization, adhesion, and chemotaxis. HIV infection and/or use of psychostimulants had minimal effects on the physical characteristics of SE. However, different SEs had diverse effects on the messenger RNA signature of monocytes and rapidly induced monocyte adhesion and spreading. SE from HIV infected or psychostimulants users but not HIV−Drug− SE, stimulated actin reorganization, leading to the formation of filopodia-like structures and membrane ruffles containing F-actin and vinculin that in some cases were colocalized. All SE stimulated monocyte chemotaxis to HIV secretome and activated the secretion of matrix metalloproteinases, a phenotype exacerbated by HIV infection and psychostimulant use. SE-directed regulation of cellular morphometrics and chemotaxis depended on the donor clinical status because HIV infection and psychostimulant use altered SE function. Although our inclusion criteria specified the use of cocaine, humans are poly-drug and alcohol users and our study participants used psychostimulants, marijuana, opiates, and alcohol. Thus, it is possible that the effects observed in this study may be due to one of these other substances or due to an interaction between different substances.

Pro-Inflammatory S100A9 Protein Aggregation Promoted by NCAM1 Peptide Constructs

Amyloid cascade and neuroinflammation are hallmarks of neurodegenerative diseases, and pro-inflammatory S100A9 protein is central to both of them. Here, we have shown that NCAM1 peptide constructs carrying polycationic sequences derived from Aβ peptide (KKLVFF) and PrP protein (KKRPKP) significantly promote the S100A9 amyloid self-assembly in a concentration-dependent manner by making transient interactions with individual S100A9 molecules, perturbing its native structure and acting as catalysts. Since the individual molecule misfolding is a rate-limiting step in S100A9 amyloid aggregation, the effects of the NCAM1 construct on the native S100A9 are so critical for its amyloid self-assembly. S100A9 rapid self-assembly into large aggregated clumps may prevent its amyloid tissue propagation, and by modulating S100A9 aggregation as a part of the amyloid cascade, the whole process may be effectively tuned.

The expression of S100A8/S100A9 is inducible and regulated by the Hippo/YAP pathway in squamous cell carcinomas

Background

S100A8 and S100A9, two heterodimer-forming members of the S100 family, aberrantly express in a variety of cancer types. However, little is known about the mechanism that regulates S100A8/S100A9 co-expression in cancer cells.

Methods

The expression level of S100A8/S100A9 measured in three squamous cell carcinomas (SCC) cell lines and their corresponding xenografts, as well as in 257 SCC tissues. The correlation between S100A8/S100A9, Hippo pathway and F-actin cytoskeleton were evaluated using western blot, qPCR, ChIP and Immunofluorescence staining tests. IncuCyte ZOOM long time live cell image monitoring system, qPCR and Flow Cytometry measured the effects of S100A8/S100A9 and YAP on cell proliferation, cell differentiation and apoptosis.

Results

Here, we report that through activation of the Hippo pathway, suspension and dense culture significantly induce S100A8/S100A9 co-expression and co-localization in SCC cells. Furthermore, these expressional characteristics of S100A8/S100A9 also observed in the xenografts derived from the corresponding SCC cells. Importantly, Co-expression of S100A8/S100A9 detected in 257 SCC specimens derived from five types of SCC tissues. Activation of the Hippo pathway by overexpression of Lats1, knockdown of YAP, as well as disruption of F-actin indeed obviously results in S100A8/S100A9 co-expression in attached SCC cells. Conversely, inhibition of the Hippo pathway leads to S100A8/S100A9 co-expression in a manner opposite of cell suspension and dense. In addition, we found that TEAD1 is required for YAP-induced S100A8/S100A9-expressions. The functional studies provide evidence that knockdown of S100A8/S100A9 together significantly inhibit cell proliferation but promote squamous differentiation and apoptosis.

Conclusions

Our findings demonstrate for the first time that the expression of S100A8/S100A9 is inducible by changes of cell shape and density through activation of the Hippo pathway in SCC cells. Induced S100A8/S100A9 promoted cell proliferation, inhibit cell differentiation and apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5784-0) contains supplementary material, which is available to authorized users.

S100 A9 is expressed and secreted by the oviduct epithelium, interacts with gametes and affects parameters of human sperm capacitation in vitro

Our previous findings demonstrate that some oviductal secretion proteins bind to gametes and affect sperm physiology and gamete interaction. One of these proteins possesses an estimated molecular weight of 14 kDa. The objective of this study was to isolate and identify this 14 kDa protein, to localize it in the human oviduct, to detect gamete binding sites for the protein, and to evaluate its effects on sperm capacitation parameters and gamete interaction. Explants from the human oviductal tissues of premenopausal women were cultured in the presence of [³⁵ S]-Methionine-proteins ([35S]-Met-proteins). De novo synthesized secreted [³⁵ S]-Met-proteins were isolated from the culture media by affinity chromatography using their sperm membrane binding ability and analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Using liquid chromatography-tandem mass spectrometry peptide sequencing, human S100 A9 was identified as one of the isolated proteins from the 14 kDa protein band. S100 A9 was detected in oviduct epithelium and oviduct secretion using immunohistochemistry and a Western blot. S100 A9 binding to human oocytes and spermatozoa was assessed by indirect immunofluorescence. The acrosome reaction (AR) affected S100 A9 ability to bind sperm cells. The presence of S100 A9 significantly increased both the induced AR and the sperm protein tyrosine phosphorylation, with respect to controls. However, the protein did not affect sperm-zona pellucida interaction. Results indicate that S100 A9 is present in the human oviduct and that it modulates parameters of sperm capacitation in vitro. Hence, the protein might contribute to the regulation of the reproductive process in the oviductal microenvironment.

S100A9 maintains myeloid-derived suppressor cells in chronic sepsis by inducing miR-21 and miR-181b

Myeloid-derived suppressor cells (MDSC) expand during sepsis, suppress both innate and adaptive immunity, and promote chronic immunosuppression, which characterizes the late/chronic phase of sepsis. We previously reported that the transcription factors Stat3 and C/EBPβ synergize to induces the expression of microRNA (miR)-21 and miR-181b to promote MDSC expansion in a mouse model of polymicrobial sepsis that progresses from an early/acute proinflammatory phase to a late/chronic immunosuppressive stage. We also showed that Gr1⁺CD11b⁺ cells, the precursors of MDSCs, from mice genetically deficient in the inflammatory protein S100A9 lack miR-21 or miR-181b in late sepsis, and are not immunosuppressive. In the present study, we show that S100A9 induces miR-21 and miR-181b during the late sepsis phase. We find that S100A9 associates with and stabilizes the Stat3-C/EBPβ protein complex that activates the miRNA promoters. Reconstituting Gr1⁺CD11b⁺ cells from S100A9 knockout mice with late sepsis with S100A9 protein restores the Stat3-C/EBPβ protein complex and miRNA expressions, and switches the Gr1⁺CD11b⁺ cells into the immunosuppressive, MDSC phenotype. Importantly, we find that this process requires IL-10 mediated signaling, which induces S100A9 translocation from the cytosol to the nucleus. These results demonstrate that S100A9 promotes MDSC expansion and immunosuppression in late/chronic sepsis by inducing the expression of miR-21 and miR-181b.

Plasma S100A8/A9 heterodimer is an early prognostic marker of acute kidney injury associated with cardiac surgery

AIM

We investigated whether plasma levels of the inflammation marker S100A8/A9, could predict acute kidney injury (AKI) onset in patients undergoing cardiac surgery necessitating cardiopulmonary bypass (CPB).

PATIENTS & METHODS

Plasma levels of S100A8/A9 and other neutrophil cytosolic proteins were measured in 39 patients pre- and immediately post-CPB.

RESULTS

All markers increased significantly post-CPB with S100A8/A9, S100A12 and myeloperoxidase levels significantly higher in patients who developed AKI within 7 days. S100A8/A9 had good prognostic utility for AKI, with an area under the receiver operating characteristic curve of 0.81 (95% CI: 0.676-0.949) and a cut-off value of 10.6 μg/ml (85.7% sensitivity and 75% specificity) irrespective of age.

CONCLUSION

Plasma S100A8/A9 levels immediately after cardiac surgery, can predict onset of AKI, irrespective of age.

Proinflammatory and amyloidogenic S100A9 induced by traumatic brain injury in mouse model

Traumatic brain injury (TBI) represents a significant risk factor for development of neurodegenerative diseases such as Alzheimer's and Parkinson's. The S100A9-driven amyloid-neuroinflammatory cascade occurring during primary and secondary TBI events can serve as a mechanistic link between TBI and Alzheimer's as demonstrated recently in the human brain tissues. Here by using immunohistochemistry in the controlled cortical impact TBI mouse model we have found pro-inflammatory S100A9 in the brain tissues of all mice on the first and third post-TBI days, while 70% of mice did not show any S100A9 presence on seventh post-TBI day similar to controls. This indicates that defensive mechanisms effectively cleared S100A9 in these mouse brain tissues during post-TBI recovery. By using sequential immunohistochemistry we have shown that S100A9 was produced by both neuronal and microglial cells. However, Aβ peptide deposits characteristic for Alzheimer's disease were not detected in any post-TBI animals. On the first and third post-TBI days S100A9 was found to aggregate intracellularly into amyloid oligomers, similar to what was previously observed in human TBI tissues. Complementary, by using Rayleigh scatting, intrinsic fluorescence and atomic force microscopy we demonstrated that in vitro S100A9 self-assembles into amyloid oligomers within minutes. Its amyloid aggregation is highly dependent on changes of environmental conditions such as variation of calcium levels, pH, temperature and reduction/oxidation, which might be relevant to perturbation of cellular and tissues homeostasis under TBI. Present results demonstrate that S100A9 induction mechanisms in TBI are similar in mice and humans, emphasizing that S100A9 is an important marker of brain injury and therefore can be a potential therapeutic target.

Measuring calprotectin in plasma and blood with a fully automated turbidimetric assay

Calprotectin in plasma and blood might prove to be a useful biomarker of inflammation and infection; however, automated methods for analysing the concentration of calprotectin in those materials are lacking. We have validated a fully automated turbidimetric method and present health-related reference limits. Calprotectin was measured by Siemens Advia XPT with the Bühlmann fCAL® turbo test (Bühlmann Laboratories AG, Schönenbuch, Switzerland), a particle enhanced turbidimetric immunoassay for quantification of calprotectin in fecal extracts. Plasma and serum samples were analysed directly, while whole blood was first extracted with M-PER® Mammalian Protein Extraction Reagent (ThermoFisher) and diluted with B-CAL-EX (Bühlmann). We studied analytical imprecision, estimated health-related reference limits and examined the correlation between neutrophil-calprotectin (blood-calprotectin adjusted for plasma-calprotectin) and the neutrophil count. The intermediate ('day-to-day') coefficient of variation was 3.5 and 1.0% for heparin-plasma-calprotectin at 0.52 mg/L and 3.53 mg/L, respectively, and 4.9% for heparin-blood-calprotectin at 50.2 mg/L. Health-related reference limits were 0.470-3.02 mg/L for calprotectin in heparin-plasma, 50.8-182 mg/L for calprotectin in heparin-blood, 0.534-2.41% for the ratio between them and 24.7-33.3 pg for the mean amount of calprotectin per neutrophil. Compared to heparin-plasma, calprotectin concentrations were significantly lower in EDTA-plasma and higher in serum (p < .05). Correlation between neutrophil-calprotectin and the neutrophil count was excellent. We have shown that the Bühlmann fCAL® turbo test can be used to measure calprotectin in plasma and blood.

Loss of the adhesion G-protein coupled receptor ADGRF5 in mice induces airway inflammation and the expression of CCL2 in lung endothelial cells

Background

Adhesion G-protein coupled receptor F5 (ADGRF5) was recently identified as an essential regulator of pulmonary surfactant homeostasis in alveolar type II cells. We previously showed that in addition to abnormal surfactant accumulation, Adgrf5-deficient (Adgrf5^−/−) mice exhibit emphysema-like signs, suggesting a possible role for ADGRF5 in immune regulation. Here, we extended the phenotypic analysis of Adgrf5^−/− mice to help understand its biological role in the lung, and especially in immune regulation.

Methods

Histological features of lungs were evaluated by Alcian blue and Masson’s trichrome staining. Quantitative real-time PCR (qPCR) and western blot analyses were performed to analyze the differential expression of genes/proteins related to airway inflammation in lungs between wildtype and Adgrf5^−/− mice. Acid–base status was assessed by performing blood gas tests and urine pH measurements. Inflammatory cell counting was performed using Giemsa-stained bronchoalveolar lavage cells. Serum IgE concentrations were determined by enzyme-linked immunosorbent assay. The expression of Ccl2, S100a8, S100a9, and Saa3 in primary lung endothelial cells (ECs) was determined by qPCR and/or western blotting. Finally, the effect of administrating RS504393 to 2-week-old Adgrf5^−/− mice on gene expression in the lungs was analyzed by qPCR.

Results

Adgrf5^−/− mice exhibited several features of chronic airway inflammation (mucous cell metaplasia, mucus hyperproduction, subepithelial fibrosis, respiratory acidosis, high serum IgE, mast cell accumulation, and neutrophilia) in parallel with elevated expression of genes involved in mucous cell metaplasia (Muc5ac, Muc5b, Slc26a4, and Clca1), fibrosis (Tgfb1, Col1a1, Fn1, and Tnc), and type 2 immune response (Il4, Il5, Il13, IL-25, and IL-33) at 12 and/or 30 weeks of age. In contrast, mRNA expression of Ccl2, S100a8, and S100a9 was upregulated in embryonic or neonatal Adgrf5^−/− lungs as well as in lung ECs of Adgrf5^−/− mice at 1 week of age. RS504393 treatment suppressed the upregulation of S100a8, S100a9, Slc26a4, and Il5 in Adgrf5^−/− lungs.

Conclusions

Targeted disruption of ADGRF5 results in the development of airway inflammation, which is likely mediated by the type 2 immune response and possibly CCL2-mediated inflammation. ADGRF5 also has a potential role in the regulation of genes encoding CCL2 in lung ECs, thereby maintaining immune homeostasis.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-0973-6) contains supplementary material, which is available to authorized users.

Hippocampal Mrp8/14 signaling plays a critical role in the manifestation of depressive-like behaviors in mice

Background

Depression is one of the most common mental disorders characterized mainly by low mood and loss of interest or pleasure. About a third of patients with depression do not respond to classic antidepressant treatments. Recent evidence suggests that Mrp8/14 (myeloid-related protein 8/14) plays a crucial role in cognitive dysfunction and neuroinflammatory diseases, yet its role in mood regulation remains largely uninvestigated. In the present work, we explored the potential role of Mrp8/14 in the progression of depression.

Methods

After 4 weeks of chronic unpredictable mild stress (CUMS), depressive-like symptoms and Mrp8/14 were determined. To verify the effects of Mrp8/14 on depressive-like behaviors, the inhibitor TAK-242 and recombinant Mrp8/14 were used. Furthermore, the molecular mechanisms in Mrp8/14-induced behavioral and biological changes were examined in vivo and ex vivo.

Results

Four-week CUMS contributed to the development of depressive symptoms. Mrp8 and Mrp14 were upregulated in the hippocampus and serum after exposure to CUMS. Pharmacological inhibition of Mrp14 attenuated CUMS-induced TLR4/NF-κB signaling activation and depressive-like behaviors. Furthermore, central administration of recombinant Mrp8, Mrp14, and Mrp8/14 resulted in neuroinflammation and depressive-like behaviors. Mrp8/14-provoked proinflammatory effects and depressive-like behaviors were improved by pretreatment with a TLR4 inhibitor. Moreover, pharmacological inhibition of TLR4 reduced the release of nitric oxide and reactive oxygen species in Mrp8/14-activated BV2 microglia.

Conclusions

These data suggest that the hippocampal Mrp8/14-TLR4-mediated neuroinflammation contributes to the development of depressive-like behaviors. Targeting the Mrp8/14 may be a novel promising antidepressant approach.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1296-0) contains supplementary material, which is available to authorized users.

S100A9-Driven Amyloid-Neuroinflammatory Cascade in Traumatic Brain Injury as a Precursor State for Alzheimer's Disease

Pro-inflammatory and amyloidogenic S100A9 protein is an important contributor to Alzheimer's disease (AD) pathology. Traumatic brain injury (TBI) is viewed as a precursor state for AD. Here we have shown that S100A9-driven amyloid-neuroinflammatory cascade was initiated in TBI and may serve as a mechanistic link between TBI and AD. By analyzing the TBI and AD human brain tissues, we demonstrated that in post-TBI tissues S100A9, produced by neurons and microglia, becomes drastically abundant compared to Aβ and contributes to both precursor-plaque formation and intracellular amyloid oligomerization. Conditions implicated in TBI, such as elevated S100A9 concentration, acidification and fever, provide strong positive feedback for S100A9 nucleation-dependent amyloid formation and delay in its proteinase clearance. Consequently, both intracellular and extracellular S100A9 oligomerization correlated with TBI secondary neuronal loss. Common morphology of TBI and AD plaques indicated their similar initiation around multiple aggregation centers. Importantly, in AD and TBI we found S100A9 plaques without Aβ. S100A9 and Aβ plaque pathology was significantly advanced in AD cases with TBI history at earlier age, signifying TBI as a risk factor. These new findings highlight the detrimental consequences of prolonged post-TBI neuroinflammation, which can sustain S100A9-driven amyloid-neurodegenerative cascade as a specific mechanism leading to AD development.

Calprotectin (S100A8/S100A9): a key protein between inflammation and cancer

BACKGROUND

Calprotectin (S100A8/S100A9), a heterodimeric EF-hand Ca²⁺ binding protein, are abundant in cytosol of neutrophils and are involved in inflammatory processes and several cancerous pathogens.

OBJECTIVE

The purpose of the present systematic review is to evaluate the pro- and anti-tumorigenic functions of calprotectin and its relation to inflammation.

MATERIALS AND METHODS

We conducted a review of studies published in the Medline (1966-2018), Scopus (2004-2018), ClinicalTrials.gov (2008-2018) and Google Scholar (2004-2018) databases, combined with studies found in the reference lists of the included studies.

RESULTS

Elevated levels of S100A8/S100A9 were detected in inflammation, neoplastic tumor cells and various human cancers. Recent data have explained that many cancers arise from sites of infection, chronic irritation, and inflammation. The inflammatory microenvironment which largely includes calprotectin, has an essential role on high producing of inflammatory factors and then on neoplastic process and metastasis.

CONCLUSION

Scientists have shown different outcomes in inflammation, malignancy and apoptosis whether the source of the aforementioned protein is extracellular or intracellular. These findings are offering new insights that anti-inflammatory therapeutic agents and anti-tumorigenic functions of calprotectin can lead to control cancer development.

IL-10 induces an immune repressor pathway in sepsis by promoting S100A9 nuclear localization and MDSC development

The myeloid-related protein S100A9 reprograms Gr1⁺CD11b⁺ myeloid precursors into myeloid-derived suppressor cells (MDSCs) during murine sepsis. Here, we show that the immunosuppressive cytokine IL-10 supports S100A9 expression and its nuclear localization in MDSCs to function as immune repressors. To support this new concept, we showed that antibody mediated IL-10 blockade in wild-type mice after sepsis induction inhibited MDSC expansion during late sepsis, and that ectopic expression of S100A9 in Gr1⁺CD11b⁺ cells from S100A9 knockout mice switched them into the MDSC phenotype only in the presence of IL-10. Knockdown of S100A9 in MDSCs from wild-type mice with late sepsis confirmed our findings in the S100A9 knockout mice. We also found that while both IL-6 and IL-10 can activate S100A9 expression in naive Gr1⁺CD11b⁺ cells, only IL-10 can induce S100A9 nuclear localization. These results support that IL-10 drives the molecular path that generates MDSCs and enhances immunosuppression during late sepsis, and inform that targeting this immune repressor path may improve sepsis survival in mice.

Exacerbation of hepatic injury during rodent malaria by myeloid-related protein 14

Hepatic dysfunction is one of the clinical features in severe malaria. However, the mechanism of hepatic injury during malaria is still unknown. Myeloid-related protein (MRP) 14 is abundantly expressed by myeloid cells and involved in various inflammatory diseases. We previously reported that serum MRP14 is elevated in mice infected with Plasmodium berghei ANKA. In order to verify whether extracellular MRP14 is involved in the pathology of hepatic injury during rodent malaria, we intravenously administrated recombinant MRP14 (rMRP14) to mice infected with P. berghei ANKA. The administration of rMRP14 did not affect parasite number or hematocrit. On the other hand, the hepatic injury was exacerbated in rMRP14-treated mice, and their serum concentration of hepatic enzymes increased significantly more than PBS-treated controls. Immunohistochemical analysis of the liver showed that more MRP14+ macrophages accumulated in rMRP14-treated mice than PBS-treated controls after infection. The administration of rMRP14 also promotes the up-regulation of pro-inflammatory molecules in the liver, such as iNOS, IL-1β, IL-12, and TNF-α. Even in the absence of Plasmodium infection, administration of rMRP14 could induce the accumulation of MRP14+ macrophages and up-regulation of the pro-inflammatory molecules in the liver of naïve mice. The results indicate that MRP14 promotes the accumulation of MRP14+ cells and the up-regulation of pro-inflammatory molecules and NO, which amplify inflammatory cascade leading to hepatic injury. In conclusion, MRP14 is a one of key molecules for liver inflammation during rodent malaria.

Multiple sclerosis and mixed microbial infections. Direct identification of fungi and bacteria in nervous tissue

Multiple sclerosis (MS) is the prototypical inflammatory disease of the central nervous system (CNS), leading to multifocal demyelination and neurodegeneration. The etiology of this incurable disease is unknown and remains a matter of intensive research. The possibility that microbial infections, such as viruses or bacteria, can trigger an autoimmune reaction in CNS tissue has been suggested. However, the recent demonstration that bacteria are present in CNS tissue points to a direct involvement of microbial infections in the etiology of MS. In the present study, we provide the first evidence of fungal infection in CNS tissue of MS patients, and demonstrate that fungal DNA from different species can be detected in the CNS. We used, nested PCR assays together with next-generation sequencing to identify the fungal species in the nervous tissue of 10 patients with MS. Strikingly, Trichosporon mucoides was found in the majority of MS patients, and particularly high levels of this fungus were found in two patients. Importantly, T. mucoides was not detected in the CNS of control subjects. We were also able to visualize fungal structures in CNS tissue sections by immunohistochemistry using specific antifungal antibodies, which also revealed the accumulation of a number of microbial cells in microfoci. Again, microbial structures were not observed in CNS sections from controls. In addition to fungi, neural tissue from MS patients was also positive for bacteria. In conclusion, our present observations point to the novel concept that MS could be caused by polymicrobial infections. Thus, mycosis of the CNS may be accompanied by opportunistic bacterial infection, promoting neuroinflammation and directly causing focal lesions, followed by demyelination and axonal injury.

Autoinhibitory regulation of S100A8/S100A9 alarmin activity locally restricts sterile inflammation

Autoimmune diseases, such as psoriasis and arthritis, show a patchy distribution of inflammation despite systemic dysregulation of adaptive immunity. Thus, additional tissue-derived signals, such as danger-associated molecular patterns (DAMPs), are indispensable for manifestation of local inflammation. S100A8/S100A9 complexes are the most abundant DAMPs in many autoimmune diseases. However, regulatory mechanisms locally restricting DAMP activities are barely understood. We now unravel for the first time, to our knowledge, a mechanism of autoinhibition in mice and humans restricting S100-DAMP activity to local sites of inflammation. Combining protease degradation, pull-down assays, mass spectrometry, and targeted mutations, we identified specific peptide sequences within the second calcium-binding EF-hands triggering TLR4/MD2-dependent inflammation. These binding sites are free when S100A8/S100A9 heterodimers are released at sites of inflammation. Subsequently, S100A8/S100A9 activities are locally restricted by calcium-induced (S100A8/S100A9)2 tetramer formation hiding the TLR4/MD2-binding site within the tetramer interphase, thus preventing undesirable systemic effects. Loss of this autoinhibitory mechanism in vivo results in TNF-α-driven fatal inflammation, as shown by lack of tetramer formation in crossing S100A9-/- mice with 2 independent TNF-α-transgene mouse strains. Since S100A8/S100A9 is the most abundant DAMP in many inflammatory diseases, specifically blocking the TLR4-binding site of active S100 dimers may represent a promising approach for local suppression of inflammatory diseases, avoiding systemic side effects.

Inhibition of Expression of the S100A8 Gene Encoding the S100 Calcium-Binding Protein A8 Promotes Apoptosis by Suppressing the Phosphorylation of Protein Kinase B (Akt) in Endometrial Carcinoma and HEC-1A Cells

Background

The aim of this study was to investigate the expression and silencing of the S100A8 gene, which encodes the S100 calcium-binding protein A8 (S100A8), and apoptosis and phosphorylation of protein kinase B (Akt) in tissue samples of endometrial carcinoma and HEC-1A endometrial adenocarcinoma cells in vitro.

Material/Methods

Immunohistochemistry (IHC) was used to detect expression of the S100A8 protein in 74 tissue samples of endometrial cancer and 22 normal endometrial tissue samples. A stable S100A8 gene knockdown cell line was constructed using lentiviral packing short hairpin RNA (shRNA) transfected into HEC-1A cells. S100A8 mRNA and S100A8 protein levels were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting. The effects of expression of the S100A8 gene by endometrial cancer cells was investigated by the MTT assay, cell cycle and apoptotic assays, qRT-PCR, and Western blotting.

Results

IHC showed high levels of expression of S100A8 protein in endometrial carcinoma tissues, and HEC-1A adenocarcinoma cells (in G1 and G2). Increased expression of S100A8 protein was found endometrial cancer tissues compared with normal endometrial tissues (79.7% vs. 4.5%). S100A8 gene knockdown reduced cell proliferation in the HEC-1A cells compared with control cells, induced cell apoptosis, inhibited the phosphorylation of protein kinase B (Akt), and induced the expression of pro-apoptotic genes, including the cytochrome C gene, CYCS, BAD, BAX, FOXO1, FOXO3, CASP9, and CASP3.

Conclusions

In endometrial carcinoma cells, down-regulation of the S100A8 gene induced cell apoptosis via inhibition of the phosphorylated or active form of protein kinase B (Akt).

Upregulation of calprotectin in mild IgE-mediated ovalbumin hypersensitivity

Calprotectin, also known as S100A8/A9, has been linked to gut inflammation caused by IgE-mediated food hypersensitivities, but the pathophysiologic abnormalities it causes remain to be determined. We created a mild food hypersensitivity model through oral gavage of ovalbumin in Norway brown rats without using immune adjuvant. Changes in the levels of calprotectin and inflammation-associated cytokines were then observed over time. We found that fecal calprotectin as well as jejunal and liver TLR4, TNF-α, NF-κB, IL-1β, and IL-6 were upregulated in hypersensitive rats. Additionally, the influence of calprotectin on CD4⁺ T and dendritic cells was observed by co-culturing CD4⁺ T cells with dendritic cells, which revealed a shift toward increased Th2 T cells in calprotectin-treated cultures. These results suggest that calprotectin, along with other inflammatory factors, promotes the inflammation seen in mild food allergy.

S100A9 Protein Aggregates Boost Hippocampal Glutamate Modifying Monoaminergic Neurochemistry: A Glutamate Antibody Sensitive Outcome on Alzheimer-like Memory Decline

Alzheimer's disease (AD) involves dementia conceivably arising from integrated inflammatory processes, amyloidogenesis, and neuronal apoptosis. Glutamate can also cause neuronal death via excitotoxicity, and this is similarly implicated in some neurological diseases. The aim was to examine treatment with in vitro generated proinflammatory protein S100A9 aggregate species alone or with glutamate antibodies (Glu-Abs) on Morris water maze (MWM) spatial learning and memory performance in 12 month old mice. Amino acid and monoamine cerebral neurotransmitter metabolic changes were concurrently monitored. Initially, S100A9 fibrils were morphologically verified by atomic force microscopy and Thioflavin T assay. They were then administered intranasally alone or with Glu-Abs for 14 days followed by a 5 day MWM protocol before hippocampal and prefrontal cortical neurochemical analysis. S100A9 aggregates evoked spatial amnesia which correlated with disrupted glutamate and dopaminergic neurochemistry. Hippocampal glutamate release, elevation of DOPAC and HVA, as well as DOPAC/DA and HVA/DA ratios were subsequently reduced by Glu-Abs which simultaneously prevented the spatial memory deficit. The present outcomes emphasized the pathogenic nature of S100A9 fibrillar aggregates in causing spatial memory amnesia associated with enhanced hippocampal glutamate release and DA-ergic disruption in the aging brain. This finding might be exploited during dementia management through a neuroprotective strategy.

Signaling between pancreatic β cells and macrophages via S100 calcium-binding protein A8 exacerbates β-cell apoptosis and islet inflammation

Chronic low-grade inflammation in the pancreatic islets is observed in individuals with type 2 diabetes, and macrophage levels are elevated in the islets of these individuals. However, the molecular mechanisms underlying the interactions between the pancreatic β cells and macrophages and their involvement in inflammation are not fully understood. Here, we investigated the role of S100 calcium-binding protein A8 (S100A8), a member of the damage-associated molecular pattern molecules (DAMPs), in β-cell inflammation. Co-cultivation of pancreatic islets with unstimulated peritoneal macrophages in the presence of palmitate (to induce lipotoxicity) and high glucose (to induce glucotoxicity) synergistically increased the expression and release of islet-produced S100A8 in a Toll-like receptor 4 (TLR4)-independent manner. Consistently, a significant increase in the expression of the S100a8 gene was observed in the islets of diabetic db/db mice. Furthermore, the islet-derived S100A8 induced TLR4-mediated inflammatory cytokine production by migrating macrophages. When human islet cells were co-cultured with U937 human monocyte cells, the palmitate treatment up-regulated S100A8 expression. This S100A8-mediated interaction between islets and macrophages evoked β-cell apoptosis, which was ameliorated by TLR4 inhibition in the macrophages or S100A8 neutralization in the pancreatic islets. Of note, both glucotoxicity and lipotoxicity triggered S100A8 secretion from the pancreatic islets, which in turn promoted macrophage infiltration of the islets. Taken together, a positive feedback loop between islet-derived S100A8 and macrophages drives β-cell apoptosis and pancreatic islet inflammation. We conclude that developing therapeutic approaches to inhibit S100A8 may serve to prevent β-cell loss in patients with diabetes.

Proteomics Analysis of Blood Serums from Alzheimer's Disease Patients Using iTRAQ Labeling Technology

Alzheimer' disease (AD) is the most common form of dementia affecting up to 6% of the population over the age of 65. In order to discover differentially expressed proteins that might serve as potential biomarkers, the serums from AD patients and healthy controls were compared and analyzed using the proteomics approach of isobaric tagging for relative and absolute quantitation (iTRAQ). For the first time, AD biomarkers in serums are investigated in the Han Chinese population using iTRAQ labeled proteomics strategy. Twenty-two differentially expressed proteins were identified and out of which nine proteins were further validated with more sample test. Another three proteins that have been reported in the literature to be potentially associated with AD were also investigated for alteration in expression level. Functions of those proteins were mainly related to the following processes: amyloid-β (Aβ) metabolism, cholesterol transport, complement and coagulation cascades, immune response, inflammation, hemostasis, hyaluronan metabolism, and oxidative stress. These results support current views on the molecular mechanism of AD. For the first time, differential expression of zinc-alpha-2-glycoprotein (AZGP1), fibulin-1 (FBLN1), platelet basic protein (PPBP), thrombospondin-1 (THBS1), S100 calcium-binding protein A8 (S100A8), and S100 calcium-binding protein A9 (S100A9) were detected in the serums of AD patients compared with healthy controls. These proteins might play a role in AD pathophysiology and serve as potential biomarkers for AD diagnosis. Specifically, our results strengthened the crucial role of Aβ metabolism and blood coagulation in AD pathogenesis and proteins related to these two processes may be used as peripheral blood biomarkers for AD.

Pathophysiological mechanism and therapeutic role of S100 proteins in cardiac failure: a systematic review

S100 proteins are a family of highly acidic calcium-binding proteins involved in calcium handling in many tissues and organs. Some of these proteins are highly expressed in cardiac tissue, and an impairment of some specific S100 proteins has been related to heart failure. To check this hypothesis, we decided to review the literature since 2008 until May 2015. According to the studies collected, recovering S100A1 levels may enhance contractile/relaxing performance in heart failure, reverse negative force-frequency relationship, improve contractile reserve, reverse diastolic dysfunction and protect against pro-arrhythmic reductions of sarcoplasmic reticulum calcium. The safety profile of gene therapy was also confirmed. Increased S100B protein levels were related to a worse outcome in chronic heart failure. S100A8/A9 complex plasma levels, as well as other inflammatory biomarkers, were significantly higher in chronic heart failure patients. S100A2 seems to increase both contractile and relaxation performance in animal cardiomyocytes. Otherwise, S100A6 cardiac expression seems to have no effects on contractility. S100A4 KO mice showed reduced cardiac interstitial fibrosis. Data collected encourage a potential prospective application in human. These proteins could be exploited as biomarkers in stadiation and prognosis of chronic heart failure, as well as therapeutic target to rescue failing heart. Registration details The study protocol has been registered in PROSPERO ( http://www.crd.york.ac.uk/PROSPERO/ ) under registration number CRD42015027932.

Metaproteomics of Colonic Microbiota Unveils Discrete Protein Functions among Colitic Mice and Control Groups

Metaproteomics can greatly assist established high-throughput sequencing methodologies to provide systems biological insights into the alterations of microbial protein functionalities correlated with disease-associated dysbiosis of the intestinal microbiota. Here, the authors utilize the well-characterized murine T cell transfer model of colitis to find specific changes within the intestinal luminal proteome associated with inflammation. MS proteomic analysis of colonic samples permitted the identification of ≈10 000-12 000 unique peptides that corresponded to 5610 protein clusters identified across three groups, including the colitic Rag1-/- T cell recipients, isogenic Rag1-/- controls, and wild-type mice. The authors demonstrate that the colitic mice exhibited a significant increase in Proteobacteria and Verrucomicrobia and show that such alterations in the microbial communities contributed to the enrichment of specific proteins with transcription and translation gene ontology terms. In combination with 16S sequencing, the authors' metaproteomics-based microbiome studies provide a foundation for assessing alterations in intestinal luminal protein functionalities in a robust and well-characterized mouse model of colitis, and set the stage for future studies to further explore the functional mechanisms of altered protein functionalities associated with dysbiosis and inflammation.

Microglia are required for protection against lethal coronavirus encephalitis in mice

Recent findings have highlighted the role of microglia in orchestrating normal development and refining neural network connectivity in the healthy CNS. Microglia are not only vital cells in maintaining CNS homeostasis, but also respond to injury, infection, and disease by undergoing proliferation and changes in transcription and morphology. A better understanding of the specific role of microglia in responding to viral infection is complicated by the presence of nonmicroglial myeloid cells with potentially overlapping function in the healthy brain and by the rapid infiltration of hematopoietic myeloid cells into the brain in diseased states. Here, we used an inhibitor of colony-stimulating factor 1 receptor (CSF1R) that depletes microglia to examine the specific roles of microglia in response to infection with the mouse hepatitis virus (MHV), a neurotropic coronavirus. Our results show that microglia were required during the early days after infection to limit MHV replication and subsequent morbidity and lethality. Additionally, microglia depletion resulted in ineffective T cell responses. These results reveal nonredundant, critical roles for microglia in the early innate and virus-specific T cell responses and for subsequent host protection from viral encephalitis.

Effect of calprotectin subunit S100A9 on the expression and methylation of OCLN in human melanoma cell line A-375

Increased levels of calprotectin subunits S100A8 and S100A9 have been detected in human cancers. Melanoma is the most aggressive type of skin cancer, and its treatment is challenging because of its brain metastasis. OCLN encodes occluding, which plays a major role in the formation and regulation of tight junctions. The aim of this study was to evaluate the methylation status of the OCLN promoter and its expression in A-375 melanoma cells treated with or without various concentrations of S100A9 for 24, 48, and 72 h. Total RNA was extracted, and synthesized cDNA was assessed by performing real-time PCR. MSP-PCR was performed after treatment with bisultfie. Recombinant S100A9 inhibited the proliferation of the A-375 cell line and the expression of the OCLN gene was downregulated in a time- and concentration-dependent manner. Results of MSP-PCR showed that the OCLN gene promoter in a human melanoma cell line (A-375) was semimethylated.

MRP14 is dispensable for LPS-induced shock in BALB/c mice

Myeloid-related protein (MRP) 14 and MRP8 are abundantly expressed by myeloid cells and are involved in various inflammatory disorders. Although accumulating evidence revealed the roles of MRP14 and MRP8 in inflammatory responses by using MRP14-knockout (KO) mice, the KO mice were only available in the C57BL/6 background. We established BALB/c-background MRP14-KO mice to examine if its biological functions are conserved in mice with a different genetic background. MRP14-KO BALB/c mice showed different phenotypes from the reported MRP14-KO C57BL/6 mice in terms of bone marrow cell response to LPS and peripheral leukocyte population. When an acute lethal dose of LPS was injected, the survival rate was not different between MRP14-KO and WT mice, which was also different from results previously reported on C57BL/6 mice. These results suggest that immunological functions of MRP14, and possibly also the associated molecule MRP8, are different between BALB/c and C57BL/6 mice, at least in the response to LPS.

Intracellular S100A9 Promotes Myeloid-Derived Suppressor Cells during Late Sepsis

Myeloid precursor cell reprogramming into a myeloid-derived suppressor cell (MDSC) contributes to high mortality rates in mouse and human sepsis. S100A9 mRNA and intracellular protein levels increase during early sepsis and remain elevated in Gr1⁺CD11b⁺ MDSCs after pro-inflammatory sepsis transitions to the later chronic anti-inflammatory and immunosuppressive phenotype. The purpose of this study was to determine whether intracellular S100A9 protein might sustain Gr1⁺CD11b⁺ MDSC repressor cell reprogramming during sepsis. We used a chronic model of sepsis in mice to show that S100A9 release from MDSCs and circulating phagocytes decreases after early sepsis and that targeting the S100a9 gene improves survival. Surprisingly, we find that intracellular S100A9 protein translocates from the cytosol to nucleus in Gr1⁺CD11b⁺ MDSCs during late sepsis and promotes expression of miR-21 and miR-181b immune repressor mediators. We further provide support of this immunosuppression pathway in human sepsis. This study may inform a new therapeutic target for improving sepsis outcome.

Newborn susceptibility to infection vs. disease depends on complex in vivo interactions of host and pathogen

The burden of newborn infectious disease has long been recognized as the highest across the entire human life span. The precise underlying cause is unfortunately still far from clear. A substantial body of data derived mostly from in vitro experimentation indicates "lower" host immune responses in early vs. adult life and is briefly summarized within this review. However, emerging data derived mostly from in vivo experimentation reveal that the newborn host also exhibits an exuberant immune and inflammatory response following infection when compared to the adult. In this context, it is important to emphasize that "infection" does not equate "infectious disease," as for many infections it is the host response to the infection that causes disease. This simple insight readily arranges existing evidence into cause-effect relationships that explain much of the increase in clinical suffering from infection in early life. We here briefly summarize the evidence in support of this paradigm and highlight the important implications it has for efforts to ameliorate the suffering and dying from infection in early life.

S100A8/A9 increases the mobilization of pro-inflammatory Ly6Chigh monocytes to the synovium during experimental osteoarthritis

BACKGROUND

Monocytes are dominant cells present within the inflamed synovium during osteoarthritis (OA). In mice, two functionally distinct monocyte subsets are described: pro-inflammatory Ly6C^high and patrolling Ly6C^low monocytes. Alarmins S100A8/A9 locally released by the synovium during inflammatory OA for prolonged periods may be dominant proteins involved in stimulating recruitment of Ly6C^high monocytes from the circulation to the joint. Our objective was to investigate the role of S100A8/A9 in the mobilization of Ly6C^high and Ly6C^low monocytic populations to the inflamed joint in collagenase-induced OA (CiOA).

METHOD

S100A8 was injected intra-articularly to investigate monocyte influx. CiOA was induced by injection of collagenase into knee joints of wild-type C57BL/6 (WT), and S100a9^-/- mice. Mice were sacrificed together with age-matched saline-injected control mice (n = 6/group), and expression of monocyte markers, pro-inflammatory cytokines, and chemokines was determined in the synovium using ELISA and RT-qPCR. Cells were isolated from the bone marrow (BM), spleen, blood, and synovium and monocytes were identified using FACS.

RESULTS

S100A8/A9 was highly expressed during CiOA. Intra-articular injection of S100A8 leads to elevated expression of monocyte markers and the monocyte-attracting chemokines CCL2 and CX3CL1 in the synovium. At day 7 (d7) after CiOA induction in WT mice, numbers of Ly6C^high, but not Ly6C^low monocytes, were strongly increased (7.6-fold) in the synovium compared to saline-injected controls. This coincided with strong upregulation of CCL2, which preferentially attracts Ly6C^high monocytes. In contrast, S100a9^-/- mice showed a significant increase in Ly6C^low monocytes (twofold) within the synovium at CiOA d7, whereas the number of Ly6C^high monocytes remained unaffected. In agreement with this finding, the Ly6C^low mobilization marker CX3CL1 was significantly higher within the synovium of S100a9^-/- mice. Next, we studied the effect of S100A8/A9 on release of Ly6C^high monocytes from the BM into the circulation. A 14% decrease in myeloid cells was found in WT BM at CiOA d7. No decrease in myeloid cells in S100a9^-/- BM was found, suggesting that S100A8/A9 promotes the release of myeloid populations from the BM.

CONCLUSION

Induction of OA locally leads to strongly elevated S100A8/A9 expression and an elevated influx of Ly6C^high monocytes from the BM to the synovium.

Role of S100A9 in the development of neutrophilic inflammation in asthmatics and in a murine model

S100A9 is an endogenous danger signal that promotes and exacerbates the neutrophilic inflammatory response. To investigate the role of S100A9 in neutrophilic asthma, S100A9 levels were measured in sputum from 101 steroid-naïve asthmatics using an ELISA kit and the levels were significantly correlated with percentages of neutrophils in sputum. Intranasal administration of recombinant S100A9 markedly increased neutrophil numbers at 8h and 24h later with concomitant elevation of IL-1β, IL-17, and IFN-γ levels. Treatment with an anti-S100A9 antibody restored the increased numbers of neutrophils and the increased airway resistance in OVA/CFA mice toward the levels of sham-treated mice. Concomitantly, the S100A9 and neutrophil elastase double positive cells were markedly reduced with attenuation of IL-1β, IL-17, and IFN-γ levels by the treatment with the anti-S100A9 antibody. Our data support a role of S100A9 to initiate and amplify the neutrophilic inflammation in asthma, possibly via inducing IL-1β, IL-17 and IFN-γ.

Transcriptome profiling of mouse colonic eosinophils reveals a key role for eosinophils in the induction of s100a8 and s100a9 in mucosal healing

Eosinophils are bone marrow-derived cells that have been largely implicated in Th2-associated diseases. Recent data highlights a key role for eosinophils in mucosal innate immune responses especially in the gastrointestinal (GI) tract, which is one of the largest eosinophil reservoirs in the body. Although eosinophils express and synthesize a plethora of proteins that can mediate their effector activities, the transcriptome signature of eosinophils in mucosal inflammation and subsequent repair has been considerably overlooked. We demonstrate that eosinophils are recruited to the colon in acute inflammatory stages where they promote intestinal inflammation and remain in substantial numbers throughout the mucosal healing process. Microarray analysis of primary colonic eosinophils that were sorted at distinct stages of mucosal inflammation and repair revealed dynamic regulation of colonic eosinophil mRNA expression. The clinically relevant genes s100a8 and s100a9 were strikingly increased in colonic eosinophils (up to 550-fold and 80-fold, respectively). Furthermore, local and systemic expression of s100a8 and s100a9 were nearly diminished in eosinophil-deficient ΔdblGATA mice, and were re-constituted upon adoptive transfer of eosinophils. Taken together, these data may provide new insight into the involvement of eosinophils in colonic inflammation and repair, which may have diagnostic and therapeutic implications.

S100A12-CD36 axis: A novel player in the pathogenesis of atherosclerosis?

S100A12 is a member of the S100 family of EF-hand calcium-binding proteins and have a variety of intracellular and extracellular activities. It exerts its proinflammatory effects by binding to the receptor for advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR4). CD36 is a class B scavenger receptor that acts as a fatty acid transporter. Both S100A12 and CD36 are implicated in vascular inflammation and atherosclerosis. It has recently been demonstrated that S100A12 binds with high affinity to CD36. On the other hand, RAGE and TLR4 play a key role in the regulation of CD36 expression. These observations point to the fact that S100A12 is an interesting molecular target for the development of therapeutics. This Cytokine stimulus will focus on the possible mechanisms of S100A12-CD36 axis in the pathogenesis of atherosclerosis.

Pathogenic implications of distinct patterns of iron and zinc in chronic MS lesions

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) in which oligodendrocytes, the CNS cells that stain most robustly for iron and myelin are the targets of injury. Metals are essential for normal CNS functioning, and metal imbalances have been linked to demyelination and neurodegeneration. Using a multidisciplinary approach involving synchrotron techniques, iron histochemistry and immunohistochemistry, we compared the distribution and quantification of iron and zinc in MS lesions to the surrounding normal appearing and periplaque white matter, and assessed the involvement of these metals in MS lesion pathogenesis. We found that the distribution of iron and zinc is heterogeneous in MS plaques, and with few remarkable exceptions they do not accumulate in chronic MS lesions. We show that brain iron tends to decrease with increasing age and disease duration of MS patients; reactive astrocytes organized in large astrogliotic areas in a subset of smoldering and inactive plaques accumulate iron and safely store it in ferritin; a subset of smoldering lesions do not contain a rim of iron-loaded macrophages/microglia; and the iron content of shadow plaques varies with the stage of remyelination. Zinc in MS lesions was generally decreased, paralleling myelin loss. Iron accumulates concentrically in a subset of chronic inactive lesions suggesting that not all iron rims around MS lesions equate with smoldering plaques. Upon degeneration of iron-loaded microglia/macrophages, astrocytes may form an additional protective barrier that may prevent iron-induced oxidative damage.