S100A12 and soluble receptor for advanced glycation end products levels during human severe sepsis

Risk factors, biomarkers, and mechanisms for persistent inflammation, immunosuppression, and catabolism syndrome (PICS): a systematic review and meta-analysis

INTRODUCTION

Persistent inflammation, immunosuppression, and catabolism syndrome (PICS) has been proposed as an endotype of chronic critical illness (CCI). The aim of this systematic review is to synthesise the available evidence of risk factors, biomarkers, and biological mechanisms underlying PICS.

METHODS

MEDLINE, CENTRAL, and EMBASE were searched on June 2, 2023. Our population of interest was adult intensive care unit survivors. The exposure group was patients with PICS and the comparator group was patients with no PICS, CCI, or rapid recovery. Mean differences were pooled for each biomarker using a random effects DerSimonian-Laird method. Risk of bias assessment was done using the Newcastle-Ottawa Scale.

RESULTS

Six papers were included. Five were single-centre retrospective cohort studies, and one was a prospective cohort study, with sample sizes ranging from 22 to 391 patients. Two studies showed an increased incidence of PICS with age, and two studies showed an association between PICS and Charlson Comorbidity Index scores. PICS was associated with requiring mechanical ventilation in four studies. Meta-analysis showed a 34.4 mg L-1 higher C-reactive protein (95% confidence interval [CI] 12.7-56.2 mg L-1; P<0.01), a 4.4 g L-1 lower albumin (95% CI 0.5-8.3 g L-1; P<0.01), and a 0.36×109 L-1 lower lymphocyte count (95% CI 0.25-0.47×109 L-1; P=0.01) in the PICS compared with the non-PICS group. There are a large variety of other potential biomarkers but limited validation studies. The overall quality of evidence is limited, and these results should be interpreted accordingly.

CONCLUSIONS

While older patients and those with co-morbidities could be at greater risk for PICS, acquired risk factors, such as injury severity, are potentially more predictive of PICS than intrinsic patient characteristics. There are many potential biomarkers for PICS, but limited validation studies have been conducted. Persistent myeloid-derived suppressor cell expansion, the continual release of danger-associated molecular patterns and pathogen-associated molecular patterns propagating inflammation, and bioenergetic failure are all mechanisms underlying PICS that could offer potential for novel biomarkers and therapeutic interventions.

CLINICAL TRIAL REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO; CRD42023427749).

Elucidating common pathogenic transcriptional networks in infective endocarditis and sepsis: integrated insights from biomarker discovery and single-cell RNA sequencing

Background

Infective Endocarditis (IE) and Sepsis are two closely related infectious diseases, yet their shared pathogenic mechanisms at the transcriptional level remain unclear. This research gap poses a barrier to the development of refined therapeutic strategies and drug innovation.

Methods

This study employed a collaborative approach using both microarray data and single-cell RNA sequencing (scRNA-seq) data to identify biomarkers for IE and Sepsis. It also offered an in-depth analysis of the roles and regulatory patterns of immune cells in these diseases.

Results

We successfully identified four key biomarkers correlated with IE and Sepsis, namely CD177, IRAK3, RNASE2, and S100A12. Further investigation revealed the central role of Th1 cells, B cells, T cells, and IL-10, among other immune cells and cytokines, in the pathogenesis of these conditions. Notably, the small molecule drug Matrine exhibited potential therapeutic effects by targeting IL-10. Additionally, we discovered two Sepsis subgroups with distinct inflammatory responses and therapeutic strategies, where CD177 demonstrated significant classification value. The reliability of CD177 as a biomarker was further validated through qRT-PCR experiments.

Conclusion

This research not only paves the way for early diagnosis and treatment of IE and Sepsis but also underscores the importance of identifying shared pathogenic mechanisms and novel therapeutic targets at the transcriptional level. Despite limitations in data volume and experimental validation, these preliminary findings add new perspectives to our understanding of these complex diseases.

Increased Production of Interleukin-10 and Tumor Necrosis Factor-Alpha in Stimulated Peripheral Blood Mononuclear Cells after Inhibition of S100A12

Sepsis may induce immunosuppression and result in death. S100A12 can bind to the receptor for advanced glycation end-products (RAGE) and Toll-like receptor (TLR)4 following induction of various inflammatory responses. It is unclear whether S100A12 significantly influences the immune system, which may be associated with sepsis-related mortality. We measured plasma S100A12 levels and cytokine responses (mean ± standard error mean) of lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) after S100A12 inhibition in healthy controls and patients with sepsis on days one and seven. Day one plasma soluble RAGE (sRAGE) and S100A12 levels in patients with sepsis were significantly higher than those in controls (2481.3 ± 295.0 vs. 1273.0 ± 108.2 pg/mL, p < 0.001; 530.3 ± 18.2 vs. 310.1 ± 28.1 pg/mL, p < 0.001, respectively). Day seven plasma S100A12 levels in non-survivors were significantly higher than those in survivors (593.1 ± 12.7 vs. 499.3 ± 23.8 pg/mL, p = 0.002, respectively). In survivors, plasma sRAGE levels were significantly decreased after 6 days (2297.3 ± 320.3 vs. 1530.1 ± 219.1 pg/mL, p = 0.009, respectively), but not in non-survivors. Inhibiting S100A12 increased the production of tumor necrosis factor (TNF)-α and interleukin (IL)-10 in stimulated PBMCs for both controls and patients. Therefore, S100A12 plays an important role in sepsis pathogenesis. S100A12 may competitively bind to TLR4 and RAGE, resulting in decreased IL-10 and TNF-α production.

Long-Term Elevated Inflammatory Protein Levels in Asymptomatic SARS-CoV-2 Infected Individuals

The clinical features of SARS-CoV-2 infection range from asymptomatic to severe disease with life-threatening complications. Understanding the persistence of immune responses in asymptomatic individuals merit special attention because of their importance in controlling the spread of the infections. We here studied the antibody and T cell responses, and a wide range of inflammation markers, in 56 SARS-CoV-2 antibody-positive individuals, identified by a population screen after the first wave of SARS-CoV-2 infection. These, mostly asymptomatic individuals, were reanalyzed 7-8 months after their infection together with 115 age-matched seronegative controls. We found that 7-8 months after the infection their antibodies to SARS-CoV-2 Nucleocapsid (N) protein declined whereas we found no decrease in the antibodies to Spike receptor-binding domain (S-RBD) when compared to the findings at seropositivity identification. In contrast to antibodies to N protein, the antibodies to S-RBD correlated with the viral neutralization capacity and with CD4+ T cell responses as measured by antigen-specific upregulation of CD137 and CD69 markers. Unexpectedly we found the asymptomatic antibody-positive individuals to have increased serum levels of S100A12, TGF-alpha, IL18, and OSM, the markers of activated macrophages-monocytes, suggesting long-term persistent inflammatory effect associated with the viral infection in asymptomatic individuals. Our results support the evidence for the long-term persistence of the inflammation process and the need for post-infection clinical monitoring of SARS-CoV-2 infected asymptomatic individuals.

Dysregulated Immunity and Immunotherapy after Sepsis

Implementation of protocolized surveillance, diagnosis, and management of septic patients, and of surgical sepsis patients in particular, is shown to result in significantly increased numbers of patients surviving their initial hospitalization. Currently, most surgical sepsis patients will rapidly recover from sepsis; however, many patients will not rapidly recover, but instead will go on to develop chronic critical illness (CCI) and experience dismal long-term outcomes. The elderly and comorbid patient is highly susceptible to death or CCI after sepsis. Here, we review aspects of the Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PICS) endotype to explain the underlying pathobiology of a dysregulated immune system in sepsis survivors who develop CCI; then, we explore targets for immunomodulatory therapy.

Serum S100A12 levels are correlated with clinical severity in patients with dermatomyositis-associated interstitial lung disease

Objective

S100A12 is an emerging inflammatory disease biomarker. Interstitial lung disease (ILD) is a common, severe complication of dermatomyositis (DM). This study was performed to investigate the association between S100A12 and disease activity and prognosis in patients with DM-associated ILD (i.e., DM-ILD).

Methods

Serum S100A12 levels were measured using enzyme-linked immunosorbent assays in patients with stable DM-ILD, patients with acute exacerbation of DM-ILD (AE DM-ILD), and healthy controls (HCs). The relationships of serum S100A12 levels with C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), ferritin, high-resolution computed tomography (HRCT) scores, and pulmonary functions were evaluated by multiple unpaired t-tests and Pearson correlation.

Results

Serum S100A12 levels were higher in patients with stable DM-ILD and those with AE DM-ILD than in HCs. Serum S100A12 levels in patients with stable DM-ILD and those with AE DM-ILD were positively correlated with CRP, ESR, and ferritin. S100A12 levels were positively correlated with HRCT scores in patients with stable DM-ILD and those with AE DM-ILD, while they were negatively correlated with predicted percentages of forced vital capacity and predicted percentages of carbon monoxide diffusing capacity in those patients.

Conclusion

Our findings demonstrate the usefulness of serum S100A12 levels for assessing clinical severity and prognosis of DM-ILD.

High plasma level of S100A8/S100A9 and S100A12 at admission indicates a higher risk of death in septic shock patients

Biomarkers in sepsis for severity, prediction of outcome or reversibility of organ dysfunction are warranted. Measurements of plasma DAMP levels at admission can reflect the severity of cellular damage in septic shock, which might predict the prognosis and reduce the risk of overtreating patients with costly therapies. We measured plasma levels of two DAMPs, S100A8/S100A9 and S100A12 during the first 24 h of admission of septic shock patients. Forty-nine septic shock patients with a similar SOFA scores were selected from our sepsis database to compare a similar proportion of survivors and non-survivors. Plasma levels of S100A8/S100A9 and S100A12 were compared with healthy volunteers using in-house ELISA. Plasma levels of S100A8/S100A9 and S100A12 (5.71 [2.60-13.63] µg/mL and 0.48 [0.22-1.05] µg/mL) were higher in septic shock patients than in healthy volunteers (1.18 [0.74-1.93] µg/mL and 0.09 [0.02-0.39] µg/mL) (P < 0.0001 and P = 0.0030). Levels of S100A8/S100A9 and S100A12 in non-survivors at day 28 (11.70 [2.85-24.36] µg/mL and 0.62 [0.30-1.64] µg/mL) were significantly higher than in survivors (4.59 [2.16-7.47] µg/mL and 0.30 [0.20-0.49] µg/mL) (P = 0.0420 and P = 0.0248) and correlated well (Spearman r = 0.879, P < 0.0001). The high level of plasma calgranulins at admission in septic shock, were higher in non-survivors compared to survivors. These markers could indicate a higher risk of death when SOFA scores are similar and help the stratification of patients for improved care and therapy selection.

Calprotectin and Calgranulin C as Biomarkers of Pancreatic Tumors: Baseline Levels and Level Changes after Surgery

Pancreatic tumors and their surgical resection are associated with significant morbidity and mortality, and the biomarkers currently used for these conditions have limited sensitivity and specificity. Because calprotectin and calgranulin C serum levels have been demonstrated to be potential biomarkers of certain cancers and complications of major surgery, the levels of both proteins were tested in the current study in patients with benign and malignant pancreatic tumors that were surgically removed. The baseline serum levels and kinetics of calprotectin and calgranulin C during the 7-day postoperative period were evaluated with immunoassays in 98 adult patients who underwent pancreatic surgery. The baseline serum levels of calprotectin and calgranulin C in patients with malignant (n = 84) and benign tumors (n = 14) were significantly higher (p < 0.01) when compared to those in the healthy controls (n = 26). The serum levels of both proteins were also significantly (p < 0.05) higher in patients with benign tumors than in those with malignant tumors. After surgery, the serum levels of calprotectin and calgranulin C were significantly (p < 0.01) higher than their baseline values, and this elevation persisted throughout the seven days of the follow-up period. Interestingly, starting on day 1 of the postoperative period, the serum levels of both proteins were significantly (p < 0.05) higher in the 37 patients who developed postoperative pancreatic fistulas (POPFs) than in the patients who had uneventful recoveries (n = 61). Moreover, the serum levels of calprotectin and calgranulin C demonstrated a significant predictive value for the development of POPF; the predictive values of these two proteins were better than those of the serum level of C-reactive protein and the white blood cell count. Taken together, the results of this study suggest that calprotectin and calgranulin C serum levels are potential biomarkers for pancreatic tumors, surgical injury to the pancreatic tissue and the development of POPFs.

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

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

Glycation of Plant Proteins: Regulatory Roles and Interplay with Sugar Signalling?

Glycation can be defined as an array of non-enzymatic post-translational modifications of proteins formed by their interaction with reducing carbohydrates and carbonyl products of their degradation. Initial steps of this process rely on reducing sugars and result in the formation of early glycation products-Amadori and Heyns compounds via Schiff base intermediates, whereas their oxidative degradation or reactions of proteins with α-dicarbonyl compounds yield a heterogeneous group of advanced glycation end products (AGEs). These compounds accompany thermal processing of protein-containing foods and are known to impact on ageing, pathogenesis of diabetes mellitus and Alzheimer's disease in mammals. Surprisingly, despite high tissue carbohydrate contents, glycation of plant proteins was addressed only recently and its physiological role in plants is still not understood. Therefore, here we summarize and critically discuss the first steps done in the field of plant protein glycation during the last decade. We consider the main features of plant glycated proteome and discuss them in the context of characteristic metabolic background. Further, we address the possible role of protein glycation in plants and consider its probable contribution to protein degradation, methylglyoxal and sugar signalling, as well as interplay with antioxidant defense.

Relation of postoperative serum S100A12 levels to delirium and cognitive dysfunction occurring after hip fracture surgery in elderly patients

OBJECTIVE

Brain injury is implicated in pathogenesis of postoperative delirium (POD) and cognitive dysfunction (POCD). S100A12 is involved in inflammatory process and is recently known as a biomarker for brain injury. Herein, we clarified whether serum S100A12 levels are related to POD and POCD after hip fracture surgery in elderly patients.

MATERIALS AND METHODS

In this prospective, observational study, we gauged S100A12 levels in preoperative and postoperative serum from 186 patients and serum from 186 controls. Patients were categorized according to the presence of POD and POCD.

RESULTS

Postoperative, but not preoperative serum S100A12 levels were significantly higher in patients than in controls. There was a positive and independent correlation between postoperative C-reactive protein and S100A12 levels (t = 8.797, p < 0.001). Postoperative S10012 levels and age were independently associated with the risk of developing POD (S100A12 levels: odds ratio [OR] = 1.166, 95% confidence interval [CI] = 1.045-2.087, p = 0.001; age: OR = 1.243, 95% CI = 1.073-1.419, p = 0.012) and POCD (S100A12: OR = 1.157, 95% CI = 1.030-1.986, p = 0.003; age: OR = 1.228, 95% CI = 1.054-1.387, p = 0.014). In terms of area under receiver operating characteristic curve, postoperative S100A12 levels had a higher predictive ability than age and their combination dramatically exceeded that of each one alone.

CONCLUSIONS

Postoperative elevated serum S100A12 levels have a strong relation to inflammation and are associated independently with the development of POD and POCD, substantializing serum S100A12 as a potential biomarker for predicting POD and POCD in elderly patients undergoing hip fracture surgery.

IL-18 and S100A12 Are Upregulated in Experimental Central Retinal Vein Occlusion

Retinal vein occlusion (RVO) is a common retinal vascular disease. RVO may be complicated by pronounced ischemia that often leads to severe loss of visual function. The present work aimed at studying the retinal proteome of RVO complicated by ischemia. In six Danish Landrace pigs RVO was induced with argon laser in the right eye of each animal. As four retinal veins were occluded, the RVO best corresponded to a central retinal vein occlusion (CRVO). Left control eyes received a similar laser treatment without inducing occlusion. RVO and retinal ischemia were verified by angiography. The retinas were collected 15 days after RVO for proteomic analysis. RVO resulted in a downregulation of proteins involved in visual perception, including rhodopsin, transducin alpha chain, and peripherin-2. RVO also caused a downregulation of proteins involved in neurotransmitter transport, including glutamate decarboxylase 1 (GAD1), glutamate decarboxylase 2 (GAD2), and complexins 2⁻4. RVO lead to increased contents of proteins involved in inflammation, including interleukin-18 (IL-18), S100A12, and annexin A1 (ANXA1). Immunohistochemistry revealed a general retinal upregulation of IL-18 and ANXA1 while S100A12 was highly abundant in retinal ganglion cells in RVO. IL-18 and S100A12 are likely to be driving forces in the inflammatory response of RVO complicated by ischemia. Our findings also suggest that RVO results in compromised neurotransmission and a downregulation of proteins involved in visual perception.

Chronic Critical Illness and the Persistent Inflammation, Immunosuppression, and Catabolism Syndrome

Dysregulated host immune responses to infection often occur, leading to sepsis, multiple organ failure, and death. Some patients rapidly recover from sepsis, but many develop chronic critical illness (CCI), a debilitating condition that impacts functional outcomes and long-term survival. The “Persistent Inflammation, Immunosuppression, and Catabolism Syndrome” (PICS) has been postulated as the underlying pathophysiology of CCI. We propose that PICS is initiated by an early genomic and cytokine storm in response to microbial invasion during the early phase of sepsis. However, once source control, antimicrobial coverage, and supportive therapies have been initiated, we propose that the persistent inflammation in patients developing CCI is a result of ongoing endogenous alarmin release from damaged organs and loss of muscle mass. This ongoing alarmin and danger-associated molecular pattern signaling causes chronic inflammation and a shift in bone marrow stem cell production toward myeloid cells, contributing to chronic anemia and lymphopenia. We propose that therapeutic interventions must target the chronic organ injury and lean tissue wasting that contribute to the release of endogenous alarmins and the expansion and deposition of myeloid progenitors that are responsible for the propagation and persistence of CCI.

Suppressed MMP-9 Activity in Myocardial Infarction-Related Cardiogenic Shock Implies Diminished Rage Degradation

BACKGROUND

Receptor for advanced glycation end products (RAGE) and its cleavage fragment soluble RAGE (sRAGE) are opposite players in inflammation. Enhanced monocytic RAGE expression and decreased plasma sRAGE levels are associated with higher mortality in infarction-related cardiogenic shock. Active matrix metalloproteinase-9 (MMP-9) has been implied in RAGE ectodomain cleavage and subsequently sRAGE shedding in vitro. We investigated MMP-9 activity in myocardial infarction-induced cardiogenic shock with regard to RAGE/sRAGE regulation.

METHODS AND RESULTS

We determined MMP-9 serum activity by zymography and tissue inhibitor of matrix metalloproteinases (TIMP-1) expression by Western blot and correlated it to RAGE/sRAGE data in patients with cardiogenic shock after acute myocardial infarction (CS, n = 30), in patients with acute myocardial infarction without shock (AMI, n = 20) and in healthy volunteers (n = 20).MMP-9 activity is increased in AMI (P = 0.02 versus controls), but significantly decreased in CS with lowest levels in non-survivors (n = 13, P = 0.02 versus AMI). In all patients, MMP-9 activity correlated inversely with RAGE expression on circulating monocytes (r = -0.57; P = 0.0001; n = 50).TIMP-1 levels showed an inverse regulation in comparison to active MMP-9 with significantly decreased levels in AMI as compared with controls (P = 0.02 versus controls) and highest levels in non-survivors of CS (P <0.001 versus AMI).

CONCLUSIONS

Serum MMP-9 activity is increased in acute myocardial infarction, but markedly suppressed in cardiogenic shock. Maintaining MMP-9 activity could be a therapeutic target to limit RAGE-induced deleterious inflammation in cardiogenic shock.

Molecular Mechanisms of Mild and Severe Pneumonia: Insights from RNA Sequencing

BACKGROUND This study aimed to uncover the molecular mechanisms underlying mild and severe pneumonia by use of mRNA sequencing (RNA-seq). MATERIAL AND METHODS RNA was extracted from the peripheral blood of patients with mild pneumonia, severe pneumonia, and healthy controls. Sequencing was performed on the HiSeq4000 platform. After filtering, clean reads were mapped to the human reference genome hg19. Differentially expressed genes (DEGs) were identified between the control group and the mild or severe group. A transcription factor-gene network was constructed for each group. Biological process (BP) terms enriched by DEGs in the network were analyzed and these genes were also mapped to the Connectivity map to search for small-molecule drugs. RESULTS A total of 199 and 560 DEGs were identified from the mild group and severe group, respectively. A transcription factor-gene network consisting of 215 nodes and another network consisting of 451 nodes were constructed in the mild group and severe group, respectively, and 54 DEGs (e.g., S100A9 and S100A12) were found to be common, with consistent differential expression changes in the 2 groups. Genes in the transcription factor-gene network for the mild group were mainly enriched in 13 BP terms, especially defense and inflammatory response (e.g., S100A8) and spermatogenesis, while the top BP terms enriched by genes in the severe group include response to oxidative stress (CCL5), wound healing, and regulation of cell differentiation (CCL5), and of the cellular protein metabolic process. CONCLUSIONS S100A9 and S100A12 may have a role in the pathogenesis of pneumonia: S100A9 and CXCL1 may contribute solely in mild pneumonia, and CCL5 and CXCL11 may contribute in severe pneumonia.

The diagnostic utility and tendency of the soluble receptor for advanced glycation end products (sRAGE) in exudative pleural effusion

BACKGROUND

The soluble receptor for advanced glycation end products (sRAGE) may have an inflammatory or homeostatic function in lung tissue. The aim of this study was to assess the usefulness of sRAGE as a diagnostic marker for exudative pleural effusions, which are common manifestations of a variety of diseases.

METHODS

Patients with an undiagnosed pleural effusion were prospectively enrolled between January 2013 and January 2015. Samples of blood and pleural fluid were centrifuged and the supernatant stored at -70 °C. The levels of sRAGE in serum and pleural fluid were determined using a commercially available enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

In total 47 patients, 21 patients were diagnosed with a tuberculous effusion, and the groups diagnosed with parapneumonic or malignant effusions comprised 13 patients each. The serum sRAGE levels for tuberculosis were significantly elevated [median, 1,291 pg/mL; interquartile range (IQR), 948-1,711 pg/mL] when compared with those for both pneumonia (median, 794 pg/mL; IQR, 700-1,255 pg/mL) and lung cancer (median, 886 pg/mL; IQR, 722-1,285 pg/mL) (P=0.029). The pleural sRAGE levels for pneumonia (median, 1,763 pg/mL; IQR, 1,262-4,431 pg/mL) were lower than those for both tuberculosis (median, 5,081 pg/mL; IQR, 3,300-6,004 pg/mL) and lung cancer (median, 4,936 pg/mL; IQR, 3,282-7,018 pg/mL) (P=0.009) The receiver operating characteristic (ROC) curve analysis selected 896 pg/mL as the best cutoff value in the sRAGE serum level for tuberculosis [sensitivity, 86%; specificity 58%; area under the curve (AUC) =0.727, P=0.008]. For the pleural effusion sRAGE level, the ROC curve analysis selected 2,231 pg/mL as the best cutoff value for pneumonia (sensitivity, 91%; specificity, 62%, AUC =0.792, P=0.002).

CONCLUSIONS

Among patients with exudative effusion, pleural and serum sRAGE measurements may be useful supportive diagnostic tools in the evaluation of ambiguous pleural effusion. Furthermore, the behavior of sRAGE in the serum and pleural fluid of various pulmonary diseases suggests that sRAGE may be linked to the chronic process of lung damage and inflammation rather than acute bacterial infection.

Effect of S100A12 and soluble receptor for advanced glycation end products on the occurrence of severe acute pancreatitis

OBJECTIVE

To assess whether serum levels of S100A12 and soluble receptor for advanced glycation end products (sRAGE) could predict the severity of acute pancreatitis (AP).

METHODS

We conducted a non-interventional pilot study, including 74 AP patients and 28 healthy volunteers serving as controls. AP patients were further divided into the mild (MAP, n = 22), moderately severe (MSAP, n = 30) and severe (SAP, n = 22) groups. Peripheral blood samples were collected within 72 h after the onset of AP for the determination of S100A12, sRAGE and C-reactive protein (CRP) levels. The acute physiology and chronic health evaluation II (APACHE II) score, Balthazar computed tomography severity index (CTSI) were calculated at admission.

RESULTS

S100A12 and sRAGE levels in SAP patient were significantly higher than in controls, MAP and MSAP patients. The receiver operating characteristic (ROC) curve analysis demonstrated the predictive ability of S100A12 [sensitivity 91%, specificity 81%, the area under the ROC curve AUROC 0.9047] and sRAGE (sensitivity 57%, specificity 100%, AUROC 0.8304) for evaluating the severity of AP. S100A12 and sRAGE were correlated with APACHE II and CTSI but not with CRP. This combination of new and traditional indicators had higher accuracy than traditional indicators alone. Specifically, S100A12 and sRAGE were positively correlated with the type of organ failure (respiratory and renal failure) and might distinguish transient from persistent organ failure at admission.

CONCLUSION

S100A12 and sRAGE could be used as efficient biomarkers for the early identification of SAP.

Biomarkers of oxidation stress, inflammation, necrosis and apoptosis are associated with hepatitis B-related acute-on-chronic liver failure

BACKGROUND AND OBJECTIVE

Hepatitis B virus related acute-on-chronic liver failure is a serious condition with a high mortality. Oxidative stress, inflammation, necrosis and apoptosis may play an important role in it. This study is to investigate whether serum AOPP, S100A12, HMGB1 and sRAGE can provide diagnostic or prognostic information in HBV-related ACLF.

METHODS

We measured serum S100A12, HMGB1 and sRAGE levels in 50 patients with HBV-related ACLF, 35 patients with liver cirrhosis (LC), 35 patients with chronic hepatitis B (CHB) and 35 healthy controls by enzyme-linked immunosorbent assay. AOPP measured by spectrophotometry.

RESULTS

Significantly higher AOPP, S100A12, HMGB1 and sRAGE levels on admission were found in patients with ACLF compared with LC, CHB and healthy controls (P<0.001). In ACLF patients, they were higher in nonsurvivors than survivors (P<0.001). They had a positive relationship with total bilirubin and MELD scores. AOPP, S100A12 and HMGB1 concentrations continually declined in survivors while increased in nonsurvivors, sRAGE concentrations did not change in survivors, but gradually increased in nonsurvivors during hospitalization. ROC curve analysis showed that the four biomarkers had a higher AUC than TBIL. Multivariate Cox regression analysis demonstrated that S100A12, AOPP and sRAGE were independent risk factors for poor prognosis.

CONCLUSION

Serum AOPP, S100A12 and sRAGE maybe reflect the oxidation stress, inflammation levels in HBV-related acute-on-chronic liver failure. Increased AOPP, S100A12 and sRAGE may serve as important biological markers of worse outcome.

[Translational research in pediatric rheumatology. Current research approaches to the innate immune system]

Translational research aims at closely linking basic research and clinical observations so that important mechanistic insights identified in one field should trigger progress in the other. Particularly in the field of pediatric rheumatology this approach has significantly improved the understanding and therapy of several diseases in recent years. One focus of our research in this respect is on the structure, release mechanisms and function of damage associated molecular patterns (DAMP), particularly S100 proteins. Due to their huge potential as inflammation biomarkers for more specific diagnostics these proteins are of particular clinical interest. Overactivated cells of the innate immune system play a crucial role in the development of rheumatic diseases. Innate mechanisms, such as the generation of neutrophil extracellular traps (NETosis) were linked to the pathogenesis of inflammatory diseases, such as systemic lupus erythematosus and rheumatoid arthritis. Furthermore, it became increasingly more evident that various excessive sterile inflammatory mechanisms and reactions significantly contribute to an activation of adaptive immune responses and thus to the development of autoimmunity. Studying such potentially DAMP-dependent pathways at the interface between innate and adaptive immunity can provide a better understanding of autoinflammatory conditions in pediatric rheumatology and to identify novel targets for optimization of therapy.

Soluble RAGE and the RAGE ligands HMGB1 and S100A12 in critical illness: impact of glycemic control with insulin and relation with clinical outcome

Systemic inflammation often leads to complications in critically ill patients. Activation of the receptor for advanced glycation end-products (RAGE) generates inflammatory cytokines, proteases, and oxidative stress and may link inflammation to subsequent organ damage. Furthermore, hyperglycemia-induced oxidative stress increases RAGE ligands and RAGE expression. We hypothesized that preventing hyperglycemia during critical illness reduces the risk of excessively enhanced RAGE signaling, which could relate to clinical outcomes and risk of death. In 405 long-stay surgical intensive care unit patients randomized to intensive or conventional insulin treatment, serum concentrations of soluble RAGE (decoy receptor) and the RAGE ligands high-mobility group box 1 (HMGB1) and S100A12 were measured on admission, day 7, and last day. These were compared with levels in 71 matched control subjects and with C-reactive protein (CRP) as a routinely monitored inflammation marker. On admission, soluble RAGE, HMGB1, S100A12, and CRP were higher in patients than in controls. The HMGB1, S100A12, and CRP remained elevated throughout intensive care unit stay, whereas soluble RAGE decreased to levels lower than in controls by day 7. Unexpectedly, insulin treatment did not affect the circulating levels of these markers. In univariable analysis, elevated levels of soluble RAGE on admission were associated with adverse outcome, including circulatory failure, kidney failure, liver dysfunction, and mortality. The associations with circulatory and kidney failure remained significant in multivariable logistic regression analysis corrected for baseline risk factors. Critical illness affects components of RAGE signaling, unaffected by insulin treatment. Elevated on-admission soluble RAGE was associated with adverse outcomes.

Circulating levels of soluble receptor for advanced glycation end products and ligands of the receptor for advanced glycation end products in patients with acute liver failure

Animal studies suggest that receptor for advanced glycation end products (RAGE)-dependent mechanisms contribute to acetaminophen-induced liver damage. We examined whether circulating levels of soluble receptor for advanced glycation end products (sRAGE) or RAGE ligands, including extracellular newly identified receptor for advanced glycation end products binding protein (EN-RAGE), high-mobility group box 1 (HMGB1), and Nε-(Carboxymethyl)lysine adducts (CML), could aid in prognostication after an acetaminophen overdose. Sixty well-characterized acetaminophen-related acute liver failure (ALF) patients (30 spontaneous survivors and 30 patients who underwent transplantation and/or died) who were enrolled in the National Institutes of Health-sponsored Acute Liver Failure Study Group, were matched by age, met standard criteria for encephalopathy, and had an international normalized ratio > 1.5 were retrospectively studied. HMGB1, EN-RAGE, CML, and sRAGE were detected by enzyme-linked immunosorbent assay methods in sera from ALF patients and 30 healthy controls. Levels of sRAGE, EN-RAGE, and HMGB1 (but not CML) were significantly greater (P < 0.001) in ALF patients versus normal controls. The levels of sRAGE, HMGB1, and EN-RAGE were significantly higher (P = 0.03, P < 0.01, and P = 0.03) in patients with a systemic inflammatory response syndrome (SIRS) score > 2 versus patients with a SIRS score ≤ 2. Nevertheless, only sRAGE levels were significantly higher in patients who underwent transplantation and/or died versus spontaneous survivors (P < 0.001), and they were positively associated with conventional markers of liver disease severity. Multivariate logistic regression identified an encephalopathy grade > 2 as an independent predictor of an adverse outcome on admission (odds ratio, 13; 95% confidence interval, 2.3-73; P < 0.001). The RAGE-ligand axis may interfere with liver regeneration and should be a promising objective for further research.

The Human Antimicrobial Protein Calgranulin C Participates in Control of Helicobacter pylori Growth and Regulation of Virulence

During infectious processes, antimicrobial proteins are produced by both epithelial cells and innate immune cells. Some of these antimicrobial molecules function by targeting transition metals and sequestering these metals in a process referred to as "nutritional immunity." This chelation strategy ultimately starves invading pathogens, limiting their growth within the vertebrate host. Recent evidence suggests that these metal-binding antimicrobial molecules have the capacity to affect bacterial virulence, including toxin secretion systems. Our previous work showed that the S100A8/S100A9 heterodimer (calprotectin, or calgranulin A/B) binds zinc and represses the elaboration of the H. pylori cag type IV secretion system (T4SS). However, there are several other S100 proteins that are produced in response to infection. We hypothesized that the zinc-binding protein S100A12 (calgranulin C) is induced in response to H. pylori infection and also plays a role in controlling H. pylori growth and virulence. To test this, we analyzed gastric biopsy specimens from H. pylori-positive and -negative patients for S100A12 expression. These assays showed that S100A12 is induced in response to H. pylori infection and inhibits bacterial growth and viability in vitro by binding nutrient zinc. Furthermore, the data establish that the zinc-binding activity of the S100A12 protein represses the activity of the cag T4SS, as evidenced by the gastric cell "hummingbird" phenotype, interleukin 8 (IL-8) secretion, and CagA translocation assays. In addition, high-resolution field emission gun scanning electron microscopy (FEG-SEM) was used to demonstrate that S100A12 represses biogenesis of the cag T4SS. Together with our previous work, these data reveal that multiple S100 proteins can repress the elaboration of an oncogenic bacterial surface organelle.

Investigation of neutrophilic peptides in periprosthetic tissue by matrix-assisted laser desorption ionisation time-of-flight imaging mass spectrometry

PURPOSE

The accurate diagnosis of periprosthetic joint infection (PJI) relies on clinical investigation, laboratory parameters, radiological methods, sterile joint aspiration for synovial fluid leucocyte count and microbiological analysis and tissue sampling for histopathology. Due to the limits in specificity and sensitivity of these methods, molecular techniques and new biomarkers were introduced into the diagnostic procedure. Histological examination is related to the amount of neutrophils in the periprosthetic tissue in frozen sections and formalin-fixed paraffin embedded material (FFPE). However, the threshold of neutrophils per defined area of tissue among various studies is very inconsistent.

METHODS

We have applied matrix-assisted laser desorption ionisation time-of-flight imaging mass spectrometry (MALDI IMS) to a total of 32 periprosthetic tissue samples of patients with PJI to detect peptides associated with areas of neutrophil infiltration.

RESULTS

Specific peaks associated with a high amount of neutrophils were detected. Of these m/z peaks, four could be assigned to predictive neutrophil molecules. These peptides include annexin A1, calgizzarin (S100A11), calgranulin C (S100A12) and histone H2A. By MALDI IMS, these peptides could be shown to be co-localised with the infiltration of neutrophils in the immediate vicinity of the periprosthetic interface, whereas more distant areas did not show neutrophil invasion or infection-related peptides.

CONCLUSIONS

MALDI IMS is a new method allowing identification of neutrophil peptides in periprosthetic tissues and may be a surrogate for counting neutrophils as an objective parameter for PJI.

Placental growth factor, pregnancy-associated plasma protein-A, soluble receptor for advanced glycation end products, extracellular newly identified receptor for receptor for advanced glycation end products binding protein and high mobility group box 1 levels in patients with acute kidney injury: a cross sectional study

BACKGROUND

Placental growth factor (PlGF), pregnancy-associated plasma protein-A (PAPP-A), soluble receptor for advanced glycation end products (sRAGE), extracellular newly identified receptor for RAGE binding protein (EN-RAGE) and high mobility group box 1 (HMGB-1) are novel biomarkers in chronic kidney disease (CKD). However, their clinical significance in acute kidney injury (AKI) is unknown. The aim of this cross-sectional study was to determine whether selected biomarkers are changed in AKI patients.

METHODS

Serum PlGF, PAPP-A, sRAGE, EN-RAGE and HMGB-1 levels were assessed in 40 patients with AKI, 42 CKD 5 patients, 31 haemodialysis patients (HD) and 39 age-matched healthy controls.

RESULTS

PAPP-A was elevated in AKI (20.6 ± 16.9 mIU/L) compared with controls (9.1 ± 2.3 mIU/L, p < 0.001). PlGF was not increased in AKI (11.7 ± 7.4 pg/mL) versus controls (8.5 ± 2.4 pg/mL, n.s.), as well as sRAGE was not elevated in AKI (2400 ± 1400 pg/mL) compared with controls (1760 ± 730 pg/mL, n.s), but was lower compared with CKD 5 (3200 ± 1500 pg/mL, p < 0.05); EN-RAGE was elevated in AKI 480 ± 450 ng/mL in comparison with controls (60 ± 62 ng/mL), CKD 5 (190 ± 120 ng/mL), and HD (120 ± 100 ng/mL), all p < 0.001. Similarly, HMGB-1 was increased in AKI (5.8 ± 7.5 ng/mL) versus controls (1.7 ± 1.4 ng/mL), CKD 5 (3.2 ± 3.1 ng/mL) and HD (2.5 ± 2.1 ng/mL), all p < 0.001.In AKI group, in multivariate regression analysis: PAPP-A levels were associated with transferrin (p <0.001), negatively with albumin (p < 0.01) and prealbumin (p < 0.05); PlGF levels were associated with C--reactive protein (p < 0.001). EN-RAGE levels were associated with ferritin (p < 0.01) and orosomucoid (p = 0.02), and HMGB-1 levels with leukocyte count (p < 0.01) and negatively with proteinuria (p = 0.02).

CONCLUSIONS

In AKI patients, PAPP-A, EN-RAGE and HMGB1 are elevated, but sRAGE and PlGF are not increased. Whereas PAPP-A correlates with markers of nutrition; PlGF, EN-RAGE and HMGB-1 are related to inflammatory parameters.