Stefanie Nickl

Primary sources and immunological prerequisites for sST2 secretion in humans

AIMS Serum levels of the soluble growth stimulation gene-2 (sST2) are elevated in heart and pulmonary diseases. However, the relationship of the sST2/interleukin (IL)-33 axis and its triggers as well as its organ distribution is still not known. This study was thus designed to investigate the cellular origin and regulation of sST2 and IL-33 in vitro and in vivo. METHODS AND RESULTS sST2 and IL-33 gene expression and protein secretion were analysed in pooled organ-specific cDNAs and in primary cell cultures, respectively, by RT-PCR and ELISA technology. The strongest sST2 mRNA expression was detected in heart and lung tissues, which correlated with spontaneous secretion of sST2 protein in vitro. The inflammatory cytokines IL-1alpha, IL-1beta, and tumour necrosis factor alpha as well as supernatants of lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells led to an enhanced secretion of sST2 in cultured cardiac myocytes and lung alveolar epithelial cells. These cytokines enhanced sST2 secretion via an NFkappaB-dependent mechanism. In addition, LPS stimulation in humans in vivo induced a short-term inflammatory response that was followed by a massive enhancement of sST2 secretion. CONCLUSION These results identify the primary sources and inflammatory triggers for the enhancement of sST2 secretion and demonstrate a relationship between inflammation and the secretion of a bioactive member of the IL-1R family, both in vitro and in vivo.

Discrimination of clinical stages in non-small cell lung cancer patients by serum HSP27 and HSP70: a multi-institutional case-control study.

INTRODUCTION Lung cancer represents a major healthcare problem. Accordingly, there is an urgent need to identify serum biomarkers for early diagnosis of lung pathology. We have recently described that patients with manifest COPD evidence elevated levels of heat shock proteins (HSPs). Based on these data, we speculated whether HSPs are also increased in patients with diagnosed lung cancer. METHODS Serum levels of HSP27, phospho-HSP27 (pHSP27) and HSP70 in patients with non-small cell lung cancer (NSCLC) diagnosed at an early (stages I-II, n=37) or advanced (stages IIIA-IV, n=72) stage were determined by using ELISA. Healthy smokers (n=24), healthy never-smoker volunteers (n=33) and COPD patients (n=34) according to GOLD classification served as control population. RESULTS Serum levels of HSP27 were elevated in patients with NSCLC diagnosed at an early or advanced stage when compared with both healthy control groups (P<0.005 and P<0.0001 respectively). Statistically significant differences were furthermore found between the groups of patients with early vs. advanced stage NSCLC (P=0.0021). Serum levels of HSP70 were also significantly elevated in patients with NSCLC diagnosed at an early or at an advanced stage when compared with either healthy control groups (P=0.0028 and P<0.0001 respectively). In univariate logistic regression models including healthy subjects and patients with NSCLC, HSP70 had an area under the curve (AUC) of 0.779 (P<0.0001) and HSP27 showed an AUC of 0.870 (P<0.0001). CONCLUSION Our data suggest that serum HSP27 levels might serve as a possible tool to discriminate between early and advanced stages NSCLC.

Alpha-Gal specific IgG immune response after implantation of bioprostheses.

BACKGROUND We have previously shown that the alpha-Gal (Galalpha1.3-Galbeta1-4GlcNAc-R) epitope is a relevant xenoantigen present on bioprostheses utilized in cardiac surgery and elicits an alpha-Gal specific IgM immune response. We sought to investigate whether that immune response continues after valve implantation. MATERIALS AND METHODS We collected plasma samples from patients who underwent bioprosthesis implantation (n = 19) or mechanical valve replacement (n = 8), respectively, prior to, at 10 days and at 3 months after cardiac surgery. ELISA was utilized to quantify alpha-Gal specific IgG and IgG subclasses. 3 bioprosthetic tissue samples were obtained from patients who had to undergo re-operation within 1 week (n = 1) or at 12-15 months (n = 2) after the initial operation. We utilized confocal laser scanning microscopy (CLSM) to detect the presence of alpha-Gal epitopes (IB4) and cell nuclei (DAPI). RESULTS alpha-Gal specific IgG was significantly increased 3 months after implantation of bioprostheses compared to preoperative values (p < 0.001) and was significantly higher than alpha-Gal specific IgG levels of the control group (p < 0.05). IgG3 was the major subclass directed against alpha-Gal (p < 0.05, pre- vs. postoperative values). In CLSM analysis we demonstrated that bioprostheses explanted 1 week after implantation contained IB4/DAPI positive cells within the collagen matrix. In contrast, in patients who underwent reoperation after 12 months, porcine tissue showed a complete lack of IB4/DAPI. CONCLUSION Our results indicate that the implantation of bioprostheses elicits a specific humoral immune response against alpha-Gal bearing cells compared to controls within 3 months after cardiac surgery. The complete absence of IB4/DAPI positive structures 12 months after implantation indicates a specific degradation of alpha-Gal bearing cells through previous exposure to the human blood circuit.

Increased serum levels of HSP27 as a marker for incipient chronic obstructive pulmonary disease in young smokers

Background: Although chronic obstructive pulmonary disease (COPD) is amongst the leading causes of morbidity and mortality, no biomarkers for its early detection are known. We have recently demonstrated that COPD is accompanied by elevated serum heat shock protein (HSP) 27 levels as compared to a control population. Objectives: In an open prospective study, we investigated whether elevated HSP27 levels are associated with the early radiological signs of COPD, i.e. air trapping (AT), emphysema (E) and impaired lung function. Methods: In total, 120 apparently healthy smokers underwent lung function testing and serum sampling. Serum levels of HSP27, phospho-HSP27, CXCR2 chemokines and proteins related to inflammation, tissue remodeling and apoptosis were evaluated by ELISA. Of these 120 subjects, 94 voluntarily underwent a high-resolution computed tomography scan. Results: AT or AT and E were detected in 57.45%. Subjects with AT and E (n = 23) showed significantly higher HSP27 levels than those without any pathology [i.e. nothing abnormal detected (NAD)] (4,618 ± 1,677 vs. 3,282 ± 1,607 pg/ml; p = 0.0081). In a univariate logistic regression model including NAD and AT and E, the area under the curve of HSP27 in the receiver-operating-characteristic curve was 0.724, (0.594–0.854, 95% CI; p = 0.0033). Interestingly, proinflammatory IL-8 was elevated in those subjects with evidence of AT and E compared to those with AT and NAD. Lung function did not correlate with increased HSP27 levels or pathological radiological findings. Conclusions: HSP27 serum levels correlated with the early radiological signs of COPD, whereas lung function did not match with radiological findings or HSP27 serum levels. Serum HSP27 levels may serve as a potential marker to identify the early signs of COPD independent of lung function in young smokers.

The receptor for advanced glycation endproducts and its ligands in patients with myasthenia gravis.

OBJECTIVE Myasthenia gravis (MG) is a T- and B-cell mediated autoimmune disorder affecting the neuromuscular junction. The receptor for advanced glycation endproducts (RAGE) plays a role in the amplification of chronic inflammatory disorders and autoimmune diseases. We sought to investigate the role of RAGE and its ligands in the pathophysiology of MG. METHODS In this cross-sectional study we enrolled 42 patients with MG and 36 volunteers. We employed enzyme-linked immunosorbent assays to determine the concentration of soluble RAGE (sRAGE) and high mobility group box 1 (HMGB1) in serum of patients and volunteers. In a subpopulation of patients we measured the serum levels of endogenous secretory (es) RAGE and various RAGE ligands, such as S100B, S100A8 and advanced glycation endproducts (AGE-CML). Reported are means and standard error mean. RESULTS We found significantly reduced levels of the soluble receptors sRAGE and esRAGE in patients with MG compared to volunteers without MG (sRAGE [pg/ml] 927.2 ± 80.8 vs. 1400.1 ± 92.4; p<0.001; esRAGE [pg/ml] 273.5±24.6 vs. 449.0 ± 22.4; p<0.001). Further categorization of patients with MG according to the distribution of muscle involvement revealed the following sRAGE concentrations: generalized MG 999.4 ± 90.8 and ocular MG 696.1 ± 161.8 (vs. control; One-way ANOVA: p<0.001; Post hoc analysis: generalized vs. ocular MG: p=0.264, generalized MG vs. control: p=0.008, ocular MG vs. control: p=0.001). In patients with detectable antibodies specific for acetylcholine receptors (Anti-AChR positive) the sRAGE concentration was 970.0 ± 90.2 compared to those without (seronegative) 670.6 ± 133.1 (vs. control; One-way ANOVA: p<0.001; Post hoc analysis: Pos vs. Neg.: p=0.418, Pos vs. control: p=0.003, Neg. vs. control: p=0.008). We next investigated the role of RAGE ligands in MG. The concentrations of RAGE ligands in patients with MG and controls were as follows: (HMGB1 [ng/ml] 1.7 ± 0.1 vs. 2.1 ± 0.2; p=0.058; S100B [pg/ml] 22.5 ± 22.5 vs. 14.4 ± 9.2; p=0.698; S100A8 [pg/ml] 107.0 ± 59.3 vs. 242.5 ± 103.6; p=0.347; and AGE-CML [ng/ml] 1100.8 ± 175.1 vs. 1399.8 ± 132.8; p=0.179). CONCLUSIONS Our data suggest a role for the RAGE pathway in the pathophysiology of MG. Further studies are warranted to elucidate more about this immunological axis in patients with MG.

Paracrine Factors from Irradiated Peripheral Blood Mononuclear Cells Improve Skin Regeneration and Angiogenesis in a Porcine Burn Model

Burn wounds pose a serious threat to patients and often require surgical treatment. Skin grafting aims to achieve wound closure but requires a well-vascularized wound bed. The secretome of peripheral blood mononuclear cells (PBMCs) has been shown to improve wound healing and angiogenesis. We hypothesized that topical application of the PBMC secretome would improve the quality of regenerating skin, increase angiogenesis, and reduce scar formation after burn injury and skin grafting in a porcine model. Full-thickness burn injuries were created on the back of female pigs. Necrotic areas were excised and the wounds were covered with split-thickness mesh skin grafts. Wounds were treated repeatedly with either the secretome of cultured PBMCs (SecPBMC), apoptotic PBMCs (Apo-SecPBMC), or controls. The wounds treated with Apo-SecPBMC had an increased epidermal thickness, higher number of rete ridges, and more advanced epidermal differentiation than controls. The samples treated with Apo-SecPBMC had a two-fold increase in CD31+ cells, indicating more angiogenesis. These data suggest that the repeated application of Apo-SecPBMC significantly improves epidermal thickness, angiogenesis, and skin quality in a porcine model of burn injury and skin grafting.

Non-professional marathon running: RAGE axis and ST2 family changes in relation to open-window effect, inflammation and renal function

Conflicting data exist on the relevance of marathon (M) and half marathon (HM) running for health. The number of non-professional athletes finishing M and HM events is steadily growing. In order to investigate molecular changes occurring in amateur athletes, we enrolled 70 non-professional runners finishing a single M (34) or HM (36) event at baseline, the finish line and during recovery, and 30 controls. The measurement of the Receptor for Advanced Glycation Endproducts, Interleukin 1 receptor antagonist, ST2 and cytokeratin 18 was combined with molecules measured during clinical routine. Results were analyzed in the light of blood cell analysis, lactate measurements, correction for changes in plasma volume and body composition assessments. There were intrinsic differences in body mass index, abdominal body fat percentage and training time between M and HM runners. C-reactive protein changes in M and HM runners. While soluble RAGE, AGEs and ST2 increased immediately after the race in HM runners, HMGB1 increased in HM and M after the race and declined to baseline after a recovery period. We give insights into the regulation of various molecules involved in physical stress reactions and their possible implications for the cardiovascular system or renal function.

Anti-Thymocyte Globulin Induces Neoangiogenesis and Preserves Cardiac Function after Experimental Myocardial Infarction

Rationale Acute myocardial infarction (AMI) followed by ventricular remodeling is the major cause of congestive heart failure and death in western world countries. Objective Of relevance are reports showing that infusion of apoptotic leucocytes or anti-lymphocyte serum after AMI reduces myocardial necrosis and preserves cardiac function. In order to corroborate this therapeutic mechanism, the utilization of an immunosuppressive agent with a comparable mechanism, such as anti-thymocyte globulin (ATG) was evaluated in this study. Methods and Results AMI was induced in rats by ligation of the left anterior descending artery. Initially after the onset of ischemia, rabbit ATG (10 mg/rat) was injected intravenously. In vitro and in vivo experiments showed that ATG induced a pronounced release of pro-angiogenic and chemotactic factors. Moreover, paracrine factors released from ATG co-incubated cell cultures conferred a down-regulation of p53 in cardiac myocytes. Rats that were injected with ATG evidenced higher numbers of CD68+ macrophages in the ischemic myocardium. Animals injected with ATG evidenced less myocardial necrosis, showed a significant reduction of infarct dimension and an improvement of post-AMI remodeling after six weeks (infarct dimension 24.9% vs. 11.4%, p<0.01). Moreover, a higher vessel density in the peri-infarct region indicated a better collateralization in rats that were injected with ATG. Conclusions These data indicate that ATG, a therapeutic agent successfully applied in clinical transplant immunology, triggered cardioprotective effects after AMI that salvaged ischemic myocardium by down-regulation of p53. This might have raised the resistance against apoptotic cell death during ischemia. The combination of these mechanisms seems to be causative for improved cardiac function and less ventricular remodeling after experimental AMI.

Lipocalin-2 Serum Levels Are Increased in Acute Hepatic Failure

Lipocalin-2 (LCN-2), which is expressed in immunocytes as well as hepatocytes, is upregulated in cells under stress from infection or inflammation with increase in serum levels. We sought to investigate the relevance of LCN-2 in the setting of acute hepatic failure, particularly when addressed with the molecular adsorbent recirculating system (MARS). We measured serum LCN-2 concentrations with enzyme-linked immunosorbent assay (ELISA) in 8 patients with acute-on-chronic-liver failure (ACLF) and acute liver failure (ALF) who were treated with MARS. The controls were 14 patients with stable chronic hepatic failure (CHF). LCN-2 was determined immediately before and after the first MARS session. Baseline LCN-2 serum concentrations were significantly increased among ACLF and ALF patients as compared with CHF (P = .004 and P = .0086, respectively). There was no significant difference between the ALF and ACLF group. Moreover, serum LCN-2 levels did not change significantly during the MARS treatment. Serum LCN-2 levels, therefore, may be useful to discern acute from chronic hepatic failure and to monitor the course as well as the severity of the disease.

Early and Sustained Changes in Bone Metabolism After Severe Burn Injury

CONTEXT Severe burn injury causes a massive stress response, consecutively heightened serum levels of acute phase proteins, cortisol, and catecholamines with accompanying disturbance in calcium metabolism. OBJECTIVE Evaluation of early and prolonged changes of serum bone turnover markers (BTMs) and regulators of bone metabolism. DESIGN Longitudinal observational design. SETTING University clinic. PATIENTS A total of 32 male patients with a median age of 40.5 years and a median burned total body surface area of 40% (83% patients with full thickness burn injury). INTERVENTIONS None. MAIN OUTCOME MEASURES Comparison of changes of BTM/regulators of bone metabolism in the early (d 2–7) and prolonged (d 7–56) phases after trauma. RESULTS All investigated BTM/regulators significantly changed. During the early phase, pronounced increases were observed for serum type 1 collagen cross-linked C-telopeptide, intact N-terminal propeptide of type I procollagen, sclerostin, Dickkopf-1, bone-specific alkaline phosphatase, fibroblast growth factor 23, and intact parathyroid hormone levels, whereas 25-hydroxyvitamin D, albumin, serum, and ionized calcium levels decreased. Changes of osteoprotegerin, osteocalcin, and phosphate were less pronounced but remained significant. In the prolonged phase, changes of intact N-terminal propeptide of type I procollagen were most pronounced, followed by elevated sclerostin, osteocalcin, bone-specific alkaline phosphatase, and lesser changes for albumin levels. Calcium and ionized calcium levels tardily increased and remained within the limit of normal. In contrast, levels of intact parathyroid hormone, fibroblast growth factor 23, C-reactive protein, and to a lesser extent serum type 1 collagen cross-linked C-telopeptide and phosphate levels declined significantly during this phase of investigation. CONCLUSIONS Ongoing changes of BTM and regulators of bone metabolism suggest alterations in bone metabolism with a likely adverse influence on bone quality and structure in male patients with severe burn injuries.