Nils E. Magnusson

Gene expression profiling: monitoring transcription and translation products using DNA microarrays and proteomics

Novel and powerful technologies such as DNA microarrays and proteomics have made possible the analysis of the expression levels of multiple genes simultaneously both in health and disease. In combination, these technologies promise to revolutionize biology, in particular in the area of molecular medicine as they are expected to reveal gene regulation events involved in disease progression as well as to pinpoint potential targets for drug discovery and diagnostics. Here, we review the current status of these technologies and highlight some studies in which they have been applied in concert to the analysis of biopsy specimens.

Induction of nuclear factor-κB and its downstream genes by TNF-α and IL-1β has a pro-apoptotic role in pancreatic beta cells

Aims/hypothesisIL-1β and TNF-α contribute to pancreatic beta cell death in type 1 diabetes. Both cytokines activate the transcription factor nuclear factor-κB (NF-κB), but recent observations suggest that NF-κB blockade prevents IL-1β + IFN-γ- but not TNF-α + IFN-γ-induced beta cell apoptosis. The aim of the present study was to compare the effects of IL-1β and TNF-α on cell death and the pattern of NF-κB activation and global gene expression in beta cells.MethodsCell viability was measured after exposure to IL-1β or to TNF-α alone or in combination with IFN-γ, and blockade of NF-κB activation or protein synthesis. INS-1E cells exposed to IL-1β or TNF-α in time course experiments were used for IκB kinase (IKK) activation assay, detection of p65 NF-κB by immunocytochemistry, real-time RT-PCR and microarray analysis.ResultsBlocking NF-κB activation protected beta cells against IL-1β + IFNγ- or TNFα + IFNγ-induced apoptosis. Blocking de novo protein synthesis did not increase TNF-α- or IL-1β-induced beta cell death, in line with the observations that cytokines induced the expression of the anti-apoptotic genes A20, Iap-2 and Xiap to a similar extent. Microarray analysis of INS-1E cells treated with IL-1β or TNF-α showed similar patterns of gene expression. IL-1β, however, induced a higher rate of expression of NF-κB target genes putatively involved in beta cell dysfunction and death and a stronger activation of the IKK complex, leading to an earlier translocation of NF-κB to the nucleus.Conclusions/interpretationNF-κB activation in beta cells has a pro-apoptotic role following exposure not only to IL-1β but also to TNF-α. The more marked beta cell death induced by IL-1β is explained at least in part by higher intensity NF-κB activation, leading to increased transcription of key target genes.

Prognostic Utility of Neutrophil Gelatinase-Associated Lipocalin in Predicting Mortality and Cardiovascular Events in Patients With ST-Segment Elevation Myocardial Infarction Treated With Primary Percutaneous Coronary Intervention

OBJECTIVES The aim of this study was to investigate the prognostic role of neutrophil gelatinase-associated lipocalin (NGAL) in a large population of patients with ST-segment elevation myocardial infarction. BACKGROUND NGAL is a glycoprotein released by damaged renal tubular cells and is a sensitive maker of both clinical and subclinical acute kidney injury. New data have demonstrated that NGAL is also stored in granules of mature neutrophils, and recent data suggest that NGAL may also be involved in the development of atherosclerosis. NGAL is significantly increased in patients with myocardial infarction compared with patients with stable coronary artery disease and healthy subjects. However, the prognostic value of NGAL has never been studied in patients with myocardial infarction. METHODS We included 584 consecutive ST-segment elevation myocardial infarction patients admitted to the heart center of Gentofte University Hospital, Denmark, and treated with primary percutaneous coronary intervention, from September 2006 to December 2008. Blood samples were drawn immediately before primary percutaneous coronary intervention. Plasma NGAL levels were measured using a time-resolved immunofluorometric assay. The endpoints were all-cause mortality (n = 69) and the combined endpoints (n = 116) of major adverse cardiac events (MACE) defined as cardiovascular mortality and admission due to recurrent myocardial infarction or heart failure. The median follow-up time was 23 months (interquartile range, 20 to 24 months). RESULTS Patients with high NGAL (>75th percentile) had increased risk of all-cause mortality and MACE compared with patients with low NGAL (log-rank test, p < 0.001). After adjustment for confounding risk factors chosen by backward elimination by Cox regression analysis, high NGAL remained an independent predictor of all-cause mortality and MACE (hazard ratio: 2.00; 95% confidence interval: 1.16 to 3.44; p = 0.01 and hazard ratio: 1.51; 95% confidence interval: 1.00 to 2.30; p = 0.05, respectively). CONCLUSIONS High plasma NGAL independently predicts all-cause mortality and MACE in ST-segment elevation myocardial infarction patients treated with primary percutaneous coronary intervention.

SLC30A3 Responds to Glucose- and Zinc Variations in ß-Cells and Is Critical for Insulin Production and In Vivo Glucose-Metabolism During ß-Cell Stress

Background Ion transporters of the Slc30A- (ZnT-) family regulate zinc fluxes into sub-cellular compartments. β-cells depend on zinc for both insulin crystallization and regulation of cell mass. Methodology/Principal Findings This study examined: the effect of glucose and zinc chelation on ZnT gene and protein levels and apoptosis in β-cells and pancreatic islets, the effects of ZnT-3 knock-down on insulin secretion in a β-cell line and ZnT-3 knock-out on glucose metabolism in mice during streptozotocin-induced β-cell stress. In INS-1E cells 2 mM glucose down-regulated ZnT-3 and up-regulated ZnT-5 expression relative to 5 mM. 16 mM glucose increased ZnT-3 and decreased ZnT-8 expression. Zinc chelation by DEDTC lowered INS-1E insulin content and insulin expression. Furthermore, zinc depletion increased ZnT-3- and decreased ZnT-8 gene expression whereas the amount of ZnT-3 protein in the cells was decreased. Zinc depletion and high glucose induced apoptosis and necrosis in INS-1E cells. The most responsive zinc transporter, ZnT-3, was investigated further; by immunohistochemistry and western blotting ZnT-3 was demonstrated in INS-1E cells. 44% knock-down of ZnT-3 by siRNA transfection in INS-1E cells decreased insulin expression and secretion. Streptozotocin-treated mice had higher glucose levels after ZnT-3 knock-out, particularly in overt diabetic animals. Conclusion/Significance Zinc transporting proteins in β-cells respond to variations in glucose and zinc levels. ZnT-3, which is pivotal in the development of cellular changes as also seen in type 2 diabetes (e.g. amyloidosis in Alzheimers disease) but not previously described in β-cells, is present in this cell type, up-regulated by glucose in a concentration dependent manner and up-regulated by zinc depletion which by contrast decreased ZnT-3 protein levels. Knock-down of the ZnT-3 gene lowers insulin secretion in vitro and affects in vivo glucose metabolism after streptozotocin treatment.

Zinc transporter gene expression is regulated by pro-inflammatory cytokines: a potential role for zinc transporters in beta-cell apoptosis?

Backgroundβ-cells are extremely rich in zinc and zinc homeostasis is regulated by zinc transporter proteins. β-cells are sensitive to cytokines, interleukin-1β (IL-1β) has been associated with β-cell dysfunction and -death in both type 1 and type 2 diabetes. This study explores the regulation of zinc transporters following cytokine exposure.MethodsThe effects of cytokines IL-1β, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) on zinc transporter gene expression were measured in INS-1-cells and rat pancreatic islets. Being the more sensitive transporter, we further explored ZnT8 (Slc30A8): the effect of ZnT8 over expression on cytokine induced apoptosis was investigated as well as expression of the insulin gene and two apoptosis associated genes, BAX and BCL2.ResultsOur results showed a dynamic response of genes responsible for β-cell zinc homeostasis to cytokines: IL-1β down regulated a number of zinc-transporters, most strikingly ZnT8 in both islets and INS-1 cells. The effect was even more pronounced when mixing the cytokines. TNF-α had little effect on zinc transporter expression. IFN-γ down regulated a number of zinc transporters. Insulin expression was down regulated by all cytokines. ZnT8 over expressing cells were more sensitive to IL-1β induced apoptosis whereas no differences were observed with IFN-γ, TNF-α, or a mixture of cytokines.ConclusionThe zinc transporting system in β-cells is influenced by the exposure to cytokines. Particularly ZnT8, which has been associated with the development of diabetes, seems to be cytokine sensitive.

The impact of simulated and real microgravity on bone cells and mesenchymal stem cells

How microgravity affects the biology of human cells and the formation of 3D cell cultures in real and simulated microgravity (r- and s-µg) is currently a hot topic in biomedicine. In r- and s-µg, various cell types were found to form 3D structures. This review will focus on the current knowledge of tissue engineering in space and on Earth using systems such as the random positioning machine (RPM), the 2D-clinostat, or the NASA-developed rotating wall vessel bioreactor (RWV) to create tissue from bone, tumor, and mesenchymal stem cells. To understand the development of 3D structures, in vitro experiments using s-µg devices can provide valuable information about modulations in signal-transduction, cell adhesion, or extracellular matrix induced by altered gravity conditions. These systems also facilitate the analysis of the impact of growth factors, hormones, or drugs on these tissue-like constructs. Progress has been made in bone tissue engineering using the RWV, and multicellular tumor spheroids (MCTS), formed in both r- and s-µg, have been reported and were analyzed in depth. Currently, these MCTS are available for drug testing and proteomic investigations. This review provides an overview of the influence of µg on the aforementioned cells and an outlook for future perspectives in tissue engineering.

Plasma Neutrophil Gelatinase-Associated Lipocalinin in the General Population Association With Inflammation and Prognosis

Objective— Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein stored in granules of neutrophil leukocytes participating in inflammatory and atherosclerotic processes and possibly plaque rupture. Despite the putative role of NGAL in atherosclerosis and acute myocardial infarction, human studies of plasma NGAL are still limited. Approach and Results— We prospectively followed 5599 randomly selected men and women from the community in the fourth Copenhagen Heart Study. Plasma NGAL was measured at study entry. Participants were followed for 10 years. During follow-up, 20% died (n=1120) and 15% (n=884) developed a major adverse cardiovascular event. Plasma NGAL associated strongly with all inflammatory markers (high-sensitivity C-reactive protein, total leukocyte count, neutrophil count) and inversely with estimated glomerular filtration rate (all, P<0.001). Multivariate analysis identified neutrophil leukocyte count as the main determinant of plasma NGAL. During follow-up, participants with increasing NGAL had increased risk of all-cause mortality and major adverse cardiovascular event (both, P<0.001). Even after adjustment for confounding risk factors by Cox regression analysis, NGAL remained an independent predictor of both all-cause mortality and major adverse cardiovascular event. When added to the Framingham risk score, NGAL improved c-statistics and correctly reclassified ≈15% into more appropriate risk groups. In comparison with high-sensitivity C-reactive protein, when both markers were added to the Framingham risk score, NGAL conferred 3× to 4× the risk. Conclusions— Plasma NGAL is strongly associated with inflammation in the general population. NGAL independently associated with 10-year outcome, and when added to the Framingham risk score, NGAL both improves c-statistics and correctly reclassifies participants into more accurate risk categories.

Plasma Neutrophil Gelatinase-Associated Lipocalinin in the General Population

Objective— Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein stored in granules of neutrophil leukocytes participating in inflammatory and atherosclerotic processes and possibly plaque rupture. Despite the putative role of NGAL in atherosclerosis and acute myocardial infarction, human studies of plasma NGAL are still limited. Approach and Results— We prospectively followed 5599 randomly selected men and women from the community in the fourth Copenhagen Heart Study. Plasma NGAL was measured at study entry. Participants were followed for 10 years. During follow-up, 20% died (n=1120) and 15% (n=884) developed a major adverse cardiovascular event. Plasma NGAL associated strongly with all inflammatory markers (high-sensitivity C-reactive protein, total leukocyte count, neutrophil count) and inversely with estimated glomerular filtration rate (all, P<0.001). Multivariate analysis identified neutrophil leukocyte count as the main determinant of plasma NGAL. During follow-up, participants with increasing NGAL had increased risk of all-cause mortality and major adverse cardiovascular event (both, P<0.001). Even after adjustment for confounding risk factors by Cox regression analysis, NGAL remained an independent predictor of both all-cause mortality and major adverse cardiovascular event. When added to the Framingham risk score, NGAL improved c-statistics and correctly reclassified ≈15% into more appropriate risk groups. In comparison with high-sensitivity C-reactive protein, when both markers were added to the Framingham risk score, NGAL conferred 3× to 4× the risk. Conclusions— Plasma NGAL is strongly associated with inflammation in the general population. NGAL independently associated with 10-year outcome, and when added to the Framingham risk score, NGAL both improves c-statistics and correctly reclassifies participants into more accurate risk categories.

Plasma neutrophil gelatinase associated lipocalin (NGAL) is associated with kidney function in uraemic patients before and after kidney transplantation

BackgroundNeutrophil gelatinase associated lipocalin (NGAL) is a biomarker of kidney injury. We examined plasma levels of NGAL in a cohort of 57 kidney allograft recipients (Tx group, 39 ± 13 years), a uraemic group of 40 patients remaining on the waiting list (47 ± 11 years) and a control group of 14 healthy subjects matched for age, sex and body mass index (BMI). The kidney graft recipients were studied at baseline before transplantation and 3 and 12 months after transplantation and the uraemic group at baseline and after 12 months.MethodsNGAL was measured using a validated in-house Time-Resolved Immuno-flourometric assay (TRIFMA). Repeated measurements differed by < 10% and mean values were used for statistical analyses. Spearman rank order correlation analysis and the Kruskal-Wallis non-parametric test were used to evaluate the association of NGAL concentrations with clinical parameters.ResultsPlasma NGAL levels before transplantation in the Tx and uraemic groups were significantly higher than in the healthy controls (1,251 μg/L, 1,478 μg/L vs. 163 μg/L, p < 0.0001). In the Tx group NGAL concentrations were associated with serum creatinine (R = 0.51, p < 0.0001), duration of end-stage renal failure (R = 0.41, p = 0.002) and leukocyte count (R = 0.29, p < 0.026). At 3 and 12 months plasma NGAL concentrations declined to 223 μg/L and 243 μg/L, respectively and were associated with homocysteine (R = 0.39, p = 0.0051 and R = 0.47, p = 0.0007).ConclusionsPlasma NGAL is a novel marker of kidney function, which correlates to duration of end-stage renal failure (ESRD) and serum creatinine in uraemic patients awaiting kidney transplantation. Plasma NGAL is associated with homocysteine in transplanted patients. The prognostic value of these findings requires further studies.

Anti-Vascular Endothelial Growth Factor Therapy in Breast Cancer

Neo-angiogenesis is a critical process for tumor growth and invasion and has become a promising target in cancer therapy. This manuscript reviews three currently relevant anti-angiogenic agents targeting the vascular endothelial growth factor system: bevacizumab, ramucirumab and sorafenib. The efficacy of anti-angiogenic drugs in adjuvant therapy or as neo-adjuvant treatment has been estimated in clinical trials of advanced breast cancer. To date, the overall observed clinical improvements are unconvincing, and further research is required to demonstrate the efficacy of anti-angiogenic drugs in breast cancer treatments. The outcomes of anti-angiogenic therapy have been highly variable in terms of tumor response. New methods are needed to identify patients who will benefit from this regimen. The development of biomarkers and molecular profiling are relevant research areas that may strengthen the ability to focus anti-angiogenic therapy towards suitable patients, thereby increase the cost-effectiveness, currently estimated to be inadequate.