Recommendations for mRNA analysis of micro-dissected glomerular tufts from paraffin-embedded human kidney biopsy samples

Background

Glomeruli are excellent pre-determined natural structures for laser micro-dissection. Compartment-specific glomerular gene expression analysis of formalin-fixed paraffin-embedded renal biopsies could improve research applications. The major challenge for such studies is to obtain good-quality RNA from small amounts of starting material, as applicable for the analysis of glomerular compartments. In this work, we provide data and recommendations for an optimized workflow of glomerular mRNA analysis.

Results

With a proper resolution of the camera and screen provided by the next generation of micro-dissection systems, we are able to separate parietal epithelial cells from glomerular tufts. Selected compartment-specific transcripts (WT1 and GLEPP1 for glomerular tuft as well as PAX2 for parietal epithelial cells) seem to be reliable discriminators for these micro-dissected glomerular substructures. Using the phenol–chloroform extraction and hemalaun-stained sections (2 µm), high amounts of Bowman’s capsule transections (> 300) reveal sufficient RNA concentrations (> 300 ng mRNA) for further analysis. For comparison, in unstained sections from a number of 60 glomerular transections upwards, a minimum amount of 157 ng mRNA with a reasonable mRNA purity [A260/A280 ratio of 1.5 (1.4/1.7) median (25th/75th percentiles)] was reversely transcribed into cDNA. Comparing the effect of input RNA (20, 60, 150 and 300 micro-dissected glomerular transections), transcript expression of POLR2A significantly correlated when 60 and 150 laser micro-dissected glomerular transections were used for analysis. There was a lower inter-assay coefficient of variability for ADAMTS13, when at least 60 glomerular transections were used. According to the algorithms of geNormPlus and NormFinder, PGK1 and PPIA are more stable glomerular reference transcripts compared to GUSB, GAPDH, POLR2A, RPLPO, TBP, B2M, ACTB, 18SrRNA and HMBS.

Conclusions

Our approach implements compartment-specific glomerular mRNA expression analysis into research applications, even regarding glomerular substructures like parietal epithelial cells. We recommend using of at least 60 micro-dissected unstained glomerular or 300 hemalaun-stained Bowman’s capsule transections to obtain sufficient input mRNA for reproducible results. Hereby, the range of RNA concentrations in 60 micro-dissected glomeruli is low and appropriate normalization of C_q values using our suggested reference transcripts (PGK1 and PPIA) allows compensation with respect to different amounts of RNA purity and quantity.

Electronic supplementary material

The online version of this article (10.1186/s12867-018-0103-x) contains supplementary material, which is available to authorized users.

Glomerulocapillary miRNA response to HLA-class I antibody in vitro and in vivo

Changes in miRNA expression glomerular of capillaries during antibody-mediated rejection (ABMR) are poorly understood and could contribute to the deleterious inflammation and fibrosis of ABMR via suppression of target genes. A better understanding could lead to novel diagnostic tools and reveal novel therapeutic targets. We explored deregulated miRNAs in an glomeruloendothelial in vitro model of ABMR due to class I human leukocyte antigen (HLA) with and without complement activation. We studied a set of 16 promising candidate miRNAs in microdissected glomeruli a confirmation set of 20 human transplant biopsies (DSA+) compared to 10 matched controls without evidence for ABMR. Twelve out of these 16 glomerulocapillary miRNAs could successfully be confirmed as dysregulated in vivo with 10 upregulated (let-7c-5p, miR-28-3p, miR-30d-5p, miR-99b-5p, miR-125a-5p, miR-195-5p, miR-374b-3p, miR-484, miR-501-3p, miR-520e) and 2 downregulated (miR29b-3p, miR-885-5p) in DSA+ vs.

CONTROLS

A random forest analysis based on glomerular miRNAs identified 18/20 DSA+ and 8/10 controls correctly. This glomerulocapillary miRNA signature associated with HLA class I-DSA could improve our understanding of ABMR and be useful for diagnostic or therapeutic purposes.

Comparison of different normalization strategies for the analysis of glomerular microRNAs in IgA nephropathy

Small nucleolar RNAs (snoRNAs) have been used for normalization in glomerular microRNA (miRNA) quantification without confirmation of validity. Our aim was to identify glomerular reference miRNAs in IgA nephropathy. We compared miRNAs in human paraffin-embedded renal biopsies from patients with cellular-crescentic IgA-GN (n = 5; crescentic IgA-GN) and non-crescentic IgA-GN (n = 5; IgA-GN) to mild interstitial nephritis without glomerular abnormalities (controls, n = 5). Laser-microdissected glomeruli were used for expression profiling of 762 miRNAs by low-density TaqMan arrays (cards A and B). The comparison of different normalization methods (GeNormPlus, NormFinder, global mean and snoRNAs) in crescentic IgA-GN, IgA-GN and controls yielded similar results. However, levels of significance and the range of relative expression differed. In median, two normalization methods demonstrated similar results. GeNormPlus and NormFinder gave different top ranked reference miRNAs. Stability ranking for snoRNAs varied between cards A and B. In conclusion, we suggest the geometric mean of the most stable reference miRNAs found in GeNormPlus (miR-26b-5p), NormFinder (miR-28-5p) and snoRNAs (RNU44) as reference. It should be considered that significant differences could be missed using one particular normalization method. As a starting point for glomerular miRNA studies in IgA nephropathy we provide a library of miRNAs.

Acid Sphingomyelinase Promotes Endothelial Stress Response in Systemic Inflammation and Sepsis

The pathophysiology of sepsis involves activation of acid sphingomyelinase (SMPD1) with subsequent generation of the bioactive mediator ceramide. We herein evaluated the hypothesis that the enzyme exerts biological effects in endothelial stress response. Plasma-secreted sphingomyelinase activity, ceramide generation and lipid raft formation were measured in human microcirculatory endothelial cells (HMEC-1) stimulated with serum obtained from sepsis patients. Clustering of receptors relevant for signal transduction was studied by immuno staining. The role of SMPD1 for macrodomain formation was tested by pharmacological inhibition. To confirm the involvement of the stress enzyme, direct inhibitors (amino bisphosphonates) and specific downregulation of the gene was tested with respect to ADAMTS13 expression and cytotoxicity. Plasma activity and amount of SMPD1 were increased in septic patients dependent on clinical severity. Increased breakdown of sphingomyelin to ceramide in HMECs was observed following stimulation with serum from sepsis patients in vitro. Hydrolysis of sphingomyelin, clustering of receptor complexes, such as the CD95L/Fas-receptor, as well as formation of ceramide enriched macrodomains was abrogated using functional inhibitors (desipramine and NB6). Strikingly, the stimulation of HMECs with serum obtained from sepsis patients or mixture of proinflammatory cytokines resulted in cytotoxicity and ADAMTS13 downregulation which was abrogated using desipramine, amino bisphosphonates and genetic inhibitors. SMPD1 is involved in the dysregulation of ceramide metabolism in endothelial cells leading to macrodomain formation, cytotoxicity and downregulation of ADAMTS13 expression. Functional inhibitors, such as desipramine, are capable to improve endothelial stress response during sepsis and might be considered as a pharmacological treatment strategy to favor the outcome.

Preserved Expression of mRNA Coding von Willebrand Factor-Cleaving Protease ADAMTS13 by Selenite and Activated Protein C

In sepsis, the severity-dependent decrease of von Willebrand factor (VWF)-inactivating protease, a disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13), results in platelet aggregation and consumption, leading to sepsis-associated thrombotic microangiopathy (TMA) and organ failure. Previous reports assessing its functional deficiency have pinpointed involvement of autoantibodies or mutations to propagate thrombotic thrombocytopenic purpura (TTP). However, mechanisms of acquired ADAMTS13 deficiency during host response remain unclear. To enhance understanding of ADAMTS13 deficiency in sepsis, we evaluated changes in expression of mRNA coding ADAMTS13 during septic conditions using primary cellular sources of the protease. We hypothesized that proinflammatory cytokines and constituents of serum from septic patients affect the transcriptional level of ADAMTS13 in vitro, and previously recommended therapeutic agents as adjunctive therapy for sepsis interact therewith. Cultured hepatic stellate cells (HSCs), endothelial cells (HMEC) and human precision-cut liver slices as an ex vivo model were stimulated with sepsis prototypic cytokines, bacterial endotoxin and pooled serum obtained from septic patients. Stimulation resulted in a significant decrease in ADAMTS13 mRNA between 10% and 80% of basal transcriptional rates. Costimulation of selenite or recombinant activated protein C (APC) with serum prevented ADAMTS13 decrease in HSCs and increased ADAMTS13 transcripts in HMEC. In archived clinical samples, the activity of ADAMTS13 in septic patients treated with APC (n = 5) increased with an accompanying decrease in VWF propeptide as surrogate for improved endothelial function. In conclusion, proinflammatory conditions of sepsis repress mRNA coding ADAMTS13 and the ameliorating effect by selenite and APC may support the concept for identification of beneficial mechanisms triggered by these drugs at a molecular level.

Impact of antibiotic treatment intensity on long-term sepsis-associated kidney injury in a polymicrobial peritoneal contamination and infection model

BACKGROUND/AIMS

Long-term kidney affections after sepsis are poorly understood. Animal models for investigating kidney damage in the late phase of disease progression are limited. The aim of this study was to investigate the impact of two antibiotic regimes on persistence of kidney injury after peritonitis.

METHODS

Kidney damage was investigated 65 days after polymicrobial peritoneal contamination and infection (PCI) sepsis induction in C57BL/6 mice. Short-term antibiotic therapy (STA, 4 days) was compared to long-term (LTA, 10 days) treatment using plasma creatinine, plasma and urine neutrophil gelatinase-associated lipocalin (NGAL), urine albumin/creatinine ratio and renal histology.

RESULTS

Sepsis resulted in mortality rates of 68.2% (STA) and 61.0% (LTA). Surviving STA animals showed the most pronounced kidney damage indicated by significantly elevated levels of creatinine and acute tubular damage (ATD), whereas NGAL was significantly increased in LTA survivors only. A creatinine level above 0.3 mg/dl was used to define kidney injury, found in 21.4% of STA animals and 7.8% of LTA animals. While animals with kidney injury demonstrated significantly higher ATD scores and persistent tubular damage, no significant differences were found for plasma or urine NGAL levels or urine albumin/creatinine ratios.

CONCLUSION

Prolonged antibiotic treatment reduced the rate of ongoing peritonitis-induced kidney injury in a C57BL/6 mouse model. Plasma or urine NGAL levels were not able to identify animals with or without persistent kidney injury. The kidney injury after the PCI mouse model represents prototypic clinical findings and should be used for further studies investigating disease mechanisms.

The price of tumor control: an analysis of rare side effects of anti-CTLA-4 therapy in metastatic melanoma from the ipilimumab network

Background

Ipilimumab, a cytotoxic T-lymphocyte antigen-4 (CTLA-4) blocking antibody, has been approved for the treatment of metastatic melanoma and induces adverse events (AE) in up to 64% of patients. Treatment algorithms for the management of common ipilimumab-induced AEs have lead to a reduction of morbidity, e.g. due to bowel perforations. However, the spectrum of less common AEs is expanding as ipilimumab is increasingly applied. Stringent recognition and management of AEs will reduce drug-induced morbidity and costs, and thus, positively impact the cost-benefit ratio of the drug. To facilitate timely identification and adequate management data on rare AEs were analyzed at 19 skin cancer centers.

Methods and Findings

Patient files (n = 752) were screened for rare ipilimumab-associated AEs. A total of 120 AEs, some of which were life-threatening or even fatal, were reported and summarized by organ system describing the most instructive cases in detail. Previously unreported AEs like drug rash with eosinophilia and systemic symptoms (DRESS), granulomatous inflammation of the central nervous system, and aseptic meningitis, were documented. Obstacles included patientś delay in reporting symptoms and the differentiation of steroid-induced from ipilimumab-induced AEs under steroid treatment. Importantly, response rate was high in this patient population with tumor regression in 30.9% and a tumor control rate of 61.8% in stage IV melanoma patients despite the fact that some patients received only two of four recommended ipilimumab infusions. This suggests that ipilimumab-induced antitumor responses can have an early onset and that severe autoimmune reactions may reflect overtreatment.

Conclusion

The wide spectrum of ipilimumab-induced AEs demands doctor and patient awareness to reduce morbidity and treatment costs and true ipilimumab success is dictated by both objective tumor responses and controlling severe side effects.

Hyperresponsiveness of mice deficient in plasma-secreted sphingomyelinase reveals its pivotal role in early phase of host response

Plasma secretion of acid sphingomyelinase is a hallmark of cellular stress response resulting in the formation of membrane embedded ceramide-enriched lipid rafts and the reorganization of receptor complexes. Consistently, decompartmentalization of ceramide formation from inert sphingomyelin has been associated with signaling events and regulation of the cellular phenotype. Herein, we addressed the question of whether the secretion of acid sphingomyelinase is involved in host response during sepsis. We found an exaggerated clinical course in mice genetically deficient in acid sphingomyelinase characterized by an increased bacterial burden, an increased phagocytotic activity, and a more pronounced cytokine storm. Moreover, on a functional level, leukocyte-endothelial interaction was found diminished in sphingomyelinase-deficient animals corresponding to a distinct leukocytes’ phenotype with respect to rolling and sticking as well as expression of cellular surface proteins. We conclude that hydrolysis of membrane-embedded sphingomyelin, triggered by circulating sphingomyelinase, plays a pivotal role in the first line of defense against invading microorganisms. This function might be essential during the early phase of infection leading to an adaptive response of remote cells and tissues.

Plexiform vasculopathy of severe pulmonary arterial hypertension and microRNA expression

BACKGROUND

Recent studies have revealed that microRNAs (miRNAs) play a key role in the control of angiogenesis and vascular remodeling. Specific miRNAs in plexiform vasculopathy of severe pulmonary arterial hypertension (PAH) in humans have not yet been investigated.

METHODS

We analyzed expression of miR-143/145 (vascular smooth muscle-specific), miR-126 (endothelial-specific) and related mRNAs in plexiform (PLs) and concentric lesions (CLs), which had been laser-microdissected from specimens of formalin-fixed, paraffin-embedded, explanted lungs of PAH patients (n = 12) and unaffected controls (n = 8). Samples were analyzed by real-time polymerase chain reaction, and protein expression was determined by immunohistochemistry.

RESULTS

Expression levels of miR-143/145 and its target proteins (e.g., myocardin, smooth muscle myosin heavy chain) were found to be significantly higher in CLs than in PLs, whereas miR-126 and VEGF-A were significantly up-regulated in PLs when compared with CLs, indicating a more prominent angiogenic phenotype of PL. This correlates with a down-regulation of miR-204 as well as an up-regulation of miR-21 in PLs, which in turn corresponds to enhanced cell proliferation.

CONCLUSIONS

Our findings show that morphologic changes of plexiform vasculopathy in the end-stage PAH lung are reflected by alterations at the miRNA level.

The synthetic tie2 agonist peptide vasculotide protects against vascular leakage and reduces mortality in murine abdominal sepsis

INTRODUCTION

Angiopoietin-1 (Angpt1), the natural agonist ligand for the endothelial Tie2 receptor, is a non-redundant endothelial survival and vascular stabilization factor that reduces endothelial permeability and inhibits leukocyte-endothelium interactions. Here we evaluate the efficacy of a novel polyethylene glycol (PEG)-clustered Tie2 agonist peptide, Vasculotide (VT), to protect against vascular leakage and mortality in a murine model of polymicrobial abdominal sepsis.

METHODS

Polymicrobial abdominal sepsis in C57BL6 mice was induced by cecal-ligation-and-puncture (CLP). Mice were treated with different dosages of VT or equal volume of phosphate-buffered saline (PBS). Sham-operated animals served as time-matched controls.

RESULTS

Systemic administration of VT induced long-lasting Tie2 activation in vivo. VT protected against sepsis-induced endothelial barrier dysfunction, as evidenced by attenuation of vascular leakage and leukocyte transmigration into the peritoneal cavity. Histological analysis revealed that VT treatment ameliorated leukocyte infiltration in kidneys of septic mice, probably due to reduced endothelial adhesion molecule expression. VT-driven effects were associated with significantly improved organ function and reduced circulating cytokine levels. The endothelial-specific action of VT was supported by additional in vitro studies showing no effect of VT on either cytokine release from isolated peritoneal macrophages, or migratory capacity of isolated neutrophils. Finally, administration of VT pre-CLP (Hazard Ratio 0.39 [95% Confidence interval 0.19-0.81] P < 0.001) and post-CLP reduced mortality in septic mice (HR 0.22 [95% CI 0.06-0.83] P < 0.05).

CONCLUSIONS

We provide proof of principle in support of the efficacious use of PEGylated VT, a drug-like Tie2 receptor agonist, to counteract microvascular endothelial barrier dysfunction and reduce mortality in a clinically relevant murine sepsis model. Further studies are needed to pave the road for clinical application of this therapeutic concept.

Diminished met signaling in podocytes contributes to the development of podocytopenia in transplant glomerulopathy

Transplant glomerulopathy (TxG) can show secondary focal and segmental glomerulosclerosis (FSGS). FSGS in native kidneys is caused by podocytopenia. This study examines podocytopenia and the role of decreased paracrine Met activation on podocytes by decreased glomerular hepatocyte growth factor (HGF) levels in the development of podocytopenia in TxG. Podocytes were counted in 10 zero-hour biopsies and 10 specimens each with and without TxG. HGF/Met was examined with immunostains and quantitative RT-PCR in a set of three consecutive biopsies from 10 patients with TxG, including the diagnostic biopsy (DiagnBx) and the two previous biopsies (1stPrevBx and 2ndPrevBx). Antiapoptotic effects of HGF on podocytes were examined in vitro. Mean podocyte numbers per glomerulus were lower and glomerular volume higher in TxG. Fewer of the two preceding biopsies of the patients than of the controls contained phospho-Met(Tyr1349)-positive podocytes (2 of 8 versus 7 of 7, P = 0.0070; 4 of 9 versus 9 of 9, P = 0.0294). Glomerular HGF mRNA levels were lower in the 1stPrevBx of the patients (0.049 ± 0.083 versus 0.284 ± 0.331; P = 0.0155). In vitro, HGF stimulation of podocytes resulted in antiapoptotic phosphorylation of AKT and extracellular signal-regulated kinase (ERK) and induction of X-linked inhibitor of apoptosis protein (XIAP). Decreased antiapoptotic Met signaling in podocytes, probably due to decreased HGF secretion by glomerular epithelial cells, could contribute to podocyte loss and FSGS in TxG.

Obliterative airway remodeling: molecular evidence for shared pathways in transplanted and native lungs

Obliteration of the small airways is a largely unresolved challenge in pulmonary medicine. It represents either the irreversible cause of functional impairment or a morphologic disorder of limited importance in a multitude of diseases. Bronchiolitis obliterans is a key complication of lung transplantation. No predictive markers for the onset of obliterative remodeling are currently available. To further elucidate the molecular mechanisms of airway remodeling, compartment-specific expression patterns were analyzed in patients. For this purpose, remodeled and nonremodeled bronchioli were isolated from transplanted and nontransplanted lung explants using laser-assisted microdissection (n = 24). mRNA expression of 45 fibrosis-associated genes was measured using quantitative real-time RT-PCR. For 20 genes, protein expression was also analyzed by immunohistochemistry. Infiltrating cells were characterized at conventional histology and immunohistochemistry. Obliterative remodeling of the small airways in transplanted and nontransplanted lungs shared similar grades of chronic inflammation and pivotal fibrotic pathways such as transforming growth factor β signaling and increased collagen expression. Bone morphogenetic protein and thrombospondin signaling, and also matrix metalloproteinases and tissue inhibitor of metalloproteinases, were primarily up-regulated in obliterative airway remodeling in nontransplanted lungs. In transplanted lungs, clinical remodeled bone morphogenetic protein but nonremodeled bronchioli were characterized by a concordant up-regulation of matrix metalloproteinase-9, RANTES, and tissue inhibitor of metalloproteinase-1. These distinct expression patterns warrant further investigation as potential markers of impending airway remodeling, especially for prospective longitudinal molecular profiling.

GDF-15 is abundantly expressed in plexiform lesions in patients with pulmonary arterial hypertension and affects proliferation and apoptosis of pulmonary endothelial cells

BACKGROUND

Growth-differentiation factor-15 (GDF-15) is a stress-responsive, transforming growth factor-β-related cytokine, which has recently been reported to be elevated in serum of patients with idiopathic pulmonary arterial hypertension (IPAH). The aim of the study was to examine the expression and biological roles of GDF-15 in the lung of patients with pulmonary arterial hypertension (PAH).

METHODS

GDF-15 expression in normal lungs and lung specimens of PAH patients were studied by real-time RT-PCR and immunohistochemistry. Using laser-assisted micro-dissection, GDF-15 expression was further analyzed within vascular compartments of PAH lungs. To elucidate the role of GDF-15 on endothelial cells, human pulmonary microvascular endothelial cells (HPMEC) were exposed to hypoxia and laminar shear stress. The effects of GDF-15 on the proliferation and cell death of HPMEC were studied using recombinant GDF-15 protein.

RESULTS

GDF-15 expression was found to be increased in lung specimens from PAH patients, compared to normal lungs. GDF-15 was abundantly expressed in pulmonary vascular endothelial cells with a strong signal in the core of plexiform lesions. HPMEC responded with marked upregulation of GDF-15 to hypoxia and laminar shear stress. Apoptotic cell death of HPMEC was diminished, whereas HPMEC proliferation was either increased or decreased depending of the concentration of recombinant GDF-15 protein.

CONCLUSIONS

GDF-15 expression is increased in PAH lungs and appears predominantly located in vascular endothelial cells. The expression pattern as well as the observed effects on proliferation and apoptosis of pulmonary endothelial cells suggest a role of GDF-15 in the homeostasis of endothelial cells in PAH patients.

MicroRNA profiling using RNA from microdissected immunostained tissue

mRNA expression profiling has been used to define molecular subtypes of human breast cancer. Also microRNAs have been investigated in these breast cancer subtypes. However, little is known regarding the microRNA signature of healthy luminal and basal breast epithelial cells. Therefore, a method is described to isolate immunostained luminal and basal breast epithelial cells in formalin-fixed paraffin-embedded tissues by laser microdissection. Employing this new methodological approach, we could identify distinct microRNA profiles of luminal and basal breast epithelial cells by real-time PCR-based profiling.

Obliterative airway remodelling in transplanted and non-transplanted lungs

Obliterative airway remodelling is a morphological sequence in a variety of pulmonary diseases. Notably, bronchiolitis obliterans represents one of the key complications of lung transplantation, induced by (immigrating) myofibroblasts. A comparative expression analysis of obliterative airway remodelling in transplanted and non-transplanted patients has not been reported so far. Obliterated and unremodelled airways from explanted lungs (n = 19) from patients suffering from chronic allograft dysfunction, infection, graft-versus-host disease and toxic exposure were isolated by laser-assisted microdissection. Airways from lung allografts harvested shortly before and after transplantation (n = 4) as well as fibroblastic foci from lungs with interstitial pulmonary fibrosis (n = 4) served as references. Pre-amplified cDNA was analysed by quantitative real-time RT-PCR for expression of fibrosis, inflammation and apoptosis-associated genes. Composition of infiltrating cells and protein expression were assessed by conventional histology and immunohistochemistry. Bronchiolitis obliterans in transplanted patients showed a significant increase of BMP-7 expression (p = 0.0141 compared with controls), while TGF-beta1 and FGF-2 as well as BMP-4 and BMP-7 were up-regulated in fibroblastic foci in interstitial pulmonary fibrosis (p < 0.0424 compared with controls). Regarding other fibrosis-associated genes (BMP-6, SMAD-3, CASP-3 and CASP-9, FASLG, NF-KB1, IL-1 and IL-2) as well as cellularity and cellular composition, no significant differences between obliterative airway remodelling in transplanted and non-transplanted patients could be shown. Obliterative airway remodelling in lung allografts and in non-transplanted patients share many morphological and genetic traits. BMPs, especially BMP-7, warrant further investigation as possible markers for the aggravation of airway remodelling.

The balance between von-Willebrand factor and its cleaving protease ADAMTS13: biomarker in systemic inflammation and development of organ failure?

PURPOSE

This review investigates and highlights the activity of Willebrand factor (VWF) and its cleaving protease as biomarkers of the development of multiple organ dysfunction in infectious and noninfectious systemic inflammatory response syndrome.

STATE OF THE ART

Ultra-large VWF (ULVWF) multimers activate platelets resulting in a prothrombotic situation. Systemic inflammation is associated with increased ULVWF plasma level and a decreased ADAMTS13 activity. The potential role of ADAMTS13 as a diagnostic and prognostic marker of disseminated intravascular coagulopathy is largely underestimated.

SUMMARY

VWF is an acute phase protein and its plasma level increases in systemic inflammation. When released from endothelial cells and platelets, the native multimeric glycoprotein is mostly present in the ultralarge form (ULVWF), which may have a major clinical significance under proinflammatory conditions. ULVWF-multimers may activate endothelial cells and platelets simultaneously. The multimers undergo limited proteolysis by a specific plasma metalloprotease known as ADAMTS13 (a disintegrin and metalloprotease with thrombospondin motif), thus, in healthy individuals only marginal amounts of circulating ULVWF are detectable. Severe hereditary or acquired ADAMTS13 deficiency causes thrombotic thrombocytopenic purpura (TTP), which contributes to prothrombotic coagulation abnormalities preceding organ dysfunction systemic inflammatory response syndrome (SIRS). In proinflammatory conditions, ADAMTS13 activity decreases due to various mechanisms, (i) down regulation on a transcriptional level, (ii) proteolytic degradation, and (iii) consumption due to the high substrate level. Marked dysbalance as found in patients with severe sepsis or septic shock results in substantial amounts of plasma ULVWF. This level of dysbalance is negatively correlated with platelet count and positively correlated with the severity of inflammation and the degree of organ failure.

Constitutional mismatch repair deficiency and childhood leukemia/lymphoma--report on a novel biallelic MSH6 mutation

Biallelic mutations of mismatch repair genes cause constitutional mismatch repair deficiency associated with an increased risk for childhood leukemia/lymphoma. We report on a case with constitutional mismatch repair deficiency caused by a novel MSH6 mutation leading to a T-cell lymphoma and colonic adenocarcinoma at six and 13 years of age, respectively. A review of the literature on hematologic malignancies in constitutional mismatch repair deficiency showed that in almost half of the 47 known constitutional mismatch repair deficiency families, at least one individual is affected by a hematologic malignancy, predominantly T-cell lymphomas. However, diagnosing constitutional mismatch repair deficiency may be difficult when the first child is affected by leukemia/lymphoma, but identification of the causative germline mutation is of vital importance: (i) to identify relatives at risk and exclude an increased risk in non-mutation carriers; (ii) to prevent hematopoietic stem cell transplantation from sibling donors also carrying a biallelic germline mutation; and (iii) to implement effective surveillance programs for mutation carriers, that may reduce constitutional mismatch repair deficiency-associated mortality.

Variations in the ratio between von Willebrand factor and its cleaving protease during systemic inflammation and association with severity and prognosis of organ failure

Von Willebrand factor (VWF) and related parameters as well as the protease activity regulating its biological activity were measured in plasma of healthy controls and patients with different cause and severity of systemic inflammation to examine the efficacy of the measures to detect highly prothrombotic states including thrombotic microangiopathy (TMA), one of the sequelae of sepsis. Plasma levels of VWF increased with increasing severity of systemic inflammation, probably due to activation of the endothelium. In parallel, the proteolytic activity of VWF inactivating protease, ADAMTS13, stepwise declined with the severity of inflammation, emphasizing the role of VWF-triggered platelet aggregation on the endothelium subsequently followed by development of TMA. As a consequence, the ratio of VWF antigen level and ADAMTS13 activity was significantly higher in patients with inflammation and sepsis, suggesting that this ratio might be more useful for the diagnosis of highly prothrombotic states including TMA than VWF multimer analysis alone. These findings suggest that ADAMTS13, VWF and related parameters, even in a combined approach, might be useful for the diagnosis and the therapeutic monitoring of patients with sepsis associated thrombotic microangiopathy.

Inflammation-associated ADAMTS13 deficiency promotes formation of ultra-large von Willebrand factor

In a prospective, longitudinal study, we investigated the association between decreased ADAMTS13 activity and impaired hemostasis, as well as organ dysfunctions in patients with systemic inflammation due to extracorporeal cardiopulmonary circuit or with severe sepsis. Similar to negative acute phase proteins, ADAMTS13 activity declined stepwise according to the extent of inflammatory responses. A marked imbalance between ADAMTS13 activity and VWF antigen level was associated with the appearance of ultra-large VWF multimers in plasma, with organ dysfunction and lethality. Our data support the view that systemic inflammation results in an ADAMTS13 deficiency which activates hemostasis.

UV-resonance Raman spectroscopic study of human plasma of healthy donors and patients with thrombotic microangiopathy

Various diseases shift the composition of human plasma; hence, the relative quantification of plasma constituents offers the opportunity to use the dynamic and complex composition of plasma to gain information on novel diagnostic and prognostic factors. Since plasma contains, besides water, mostly proteins, UV-resonance Raman spectroscopy (UVRR) seems to be a suitable method for investigating plasma. With this method the signals of aromatic amino acids and proteins are selectively enhanced. In this study an UV-resonance Raman approach was used for the investigation of human plasma of healthy volunteers and patients with thrombotic microangiopathy. For comparison, selected plasma components were analyzed for a more detailed characterization of cryoprecipitates from human plasma.

Transcriptional regulation of ADAMTS13

The metalloproteinase ADAMTS13 cleaves VWF multimers instantaneously when they are released from endothelial cells. Absent or manifestly diminished proteolytic activity of ADAMTS13 results in the appearance and accumulation of ultralarge VWF multimers (ULVWFM) in plasma, characterised by the manifestation of Thrombotic Thrombocytopenic Purpura (TTP). Despite congenital defects, infections and the actions of drugs such as cyclosporine A, doxycycline and corticosteroids apparently are involved in its development. To examine the possibility of transcriptional regulation of ADAMTS13 activity, we analyzed RNA levels in various cell culture systems and the response to known and assumed modulators of gene expression. We demonstrate the expression of ADAMTS13 in liver homogenates and a parenchyma liver cell culture system Hep3B, supporting the hypothesis that liver is an important source of plasma ADAMTS13, whereas there was no alteration in gene expression after stimulation of liver cells with proinflammatory stimuli such as endotoxin, TNF-alpha, IL-6, IL-1beta as well as immuno-suppressive agents, such as cyclosporine A, a variety of steroids as well as doxycycline. Therefore, we analysed the ADAMTS13 gene for binding sites of transcription factors in silico and compared the data with those found in two sets of 24 genes considered either as differentially regulated by prototypic inflammatory regulation or as unvaried under various conditions. On the basis of these data, the promotor of ADAMTS13 features the characteristics of a gene, which remains unvaried under a variety of conditions. To our knowledge, the current data demonstrate for the first time, that an alteration in transcriptional activity is negligible in accounting for diminished proteolytic activity as observed under various experimental and, in particular, clinical conditions.

Role of increased sphingomyelinase activity in apoptosis and organ failure of patients with severe sepsis

Numerous studies support the notion that an activation of sphingomyelinases and a subsequent increase of the concentration of the bioactive lipid mediator ceramide are critical in the concert of inflammatory stimuli and to the induction of apoptosis during inflammation. Here we show that patients with severe sepsis exhibit an enhanced sphingolytic activity in comparison with controls [262 pmol/(mlxh) vs. 123.6 pmol/(mlxh), P<0.005]. During the clinical course, a further increase was paralleled by the severity of illness and by fatal outcome. Moreover, we show that oxidative stress may partially account for the increased activity through posttranslational modification of the enzyme. In a murine endotoxic shock model, administration of a low molecular weight inhibitor diminished the rise in enzymatic activity and improved the survival rate. In liver specimen, inhibition of activity correlated with a reduced rate of hepato-cellular apoptosis. Our data support the concept that activation of the plasmatic isoform of sphingomyelinase may play a critical role in the development of apoptosis and organ failure in sepsis. An inhibition of the secreted isoform of sphingomyelinase should be explored further as a potential target in the complicated puzzle of sepsis.

Synthesis and Antiapoptotic Activity of a Novel Analogue of the Neutral Sphingomyelinase Inhibitor Scyphostatin

The enantioselective synthesis of an analogue of scyphostatin, a potent inhibitor of the neutral sphingomyelinase, is described. The synthesis starts with cyclohexanone and a protected D-serine derivative. The key step is an asymmetric hydroxylation to access a hydroxycyclohexanone, which is transformed into a substituted hydroxycyclohexenone. This is converted into the scyphostatin analogue 14, a chemically and metabolically stabilised compound lacking the epoxy function of the natural congener and carrying a palmitic acid group instead of the native trienoyl residue. An evaluation of the biological activity of 14 revealed neutral sphingomyelinase inhibition in several in vivo test systems (monocytes, macrophages, hepatocytes) monitoring antiapoptotic effects and the inversion of phorbolester-induced translocation of green fluorescent protein labelled kinase (protein kinase C-alpha).