Linda Fogelstrand

Induction of proinflammatory cytokines by long-chain saturated fatty acids in human macrophages

Increased circulating free fatty acids in subjects with type 2 diabetes may contribute to activation of macrophages, and thus the development of atherosclerosis. In this study, we investigated the effect of the saturated fatty acids (SFA) palmitate, stearate, myristate and laurate, and the unsaturated fatty acid linoleate, on the production of proinflammatory cytokines in phorbol ester-differentiated THP-1 cells, a model of human macrophages. Palmitate induced secretion and mRNA expression of TNF-alpha, IL-8 and IL-1 beta, and enhanced lipopolysaccharide (LPS)-induced IL-1 beta secretion. Proinflammatory cytokine secretion was also induced by stearate, but not by the shorter chain SFA, myristate and laurate, or linoleate. Triacsin C abolished the palmitate-induced cytokine secretion, suggesting that palmitate activation to palmitoyl-CoA is required for its effect. Palmitate-induced cytokine secretion was decreased by knockdown of serine palmitoyltransferase and mimicked by C(2)-ceramide, indicating that ceramide is involved in palmitate-induced cytokine secretion. Palmitate phosphorylated p38 and JNK kinases, and blocking of these kinases with specific inhibitors diminished the palmitate-induced cytokine secretion. Palmitate also activated the AP-1 (c-Jun) transcription factor. Knockdown of MyD88 reduced the palmitate-induced IL-8, but not TNF-alpha or IL-1 beta secretion. In conclusion, our data suggest that the long-chain SFA induce proinflammatory cytokines in human macrophages via pathways involving de novo ceramide synthesis. This might contribute to the activation of macrophages in atherosclerotic plaques, especially in type 2 diabetes.

Monocytic expression of CD14 and CD18, circulating adhesion molecules and inflammatory markers in women with diabetes mellitus and impaired glucose tolerance

Aims/hypothesisType 2 diabetes is a major risk factor for cardiovascular disease. Monocyte recruitment and inflammatory activation are crucial steps in the development of atherosclerosis and several receptors are involved in these processes. The aim of this study was to investigate levels of CD14 and the β2-integrin subunits CD11b and CD18 on monocytes from women with diabetes or impaired glucose tolerance.MethodsA population-based sample of 112 Swedish women, who were aged 64 years and had diabetes mellitus or impaired or normal glucose tolerance, was investigated. Cell surface receptors were analysed with flow cytometry and serum inflammation markers and soluble adhesion molecules with enzyme-linked methods.ResultsThe monocytic CD14 expression and serum levels of C-reactive protein, IL-6 and soluble adhesion molecules were higher in the diabetes group than in the group with normal glucose tolerance. Monocytic CD18 was elevated both in the diabetes and in the impaired glucose tolerance groups. The levels of monocytic surface markers correlated with BMI and to a lesser extent with glycaemic control.Conclusions/interpretationThe increased monocytic expression of important surface receptors together with elevated serum inflammation markers supports the concept of increased inflammation in type 2 diabetes and may be an important factor for the risk of atherosclerosis.

The genomic landscape of high hyperdiploid childhood acute lymphoblastic leukemia.

High hyperdiploid (51–67 chromosomes) acute lymphoblastic leukemia (ALL) is one of the most common childhood malignancies, comprising 30% of all pediatric B cell–precursor ALL. Its characteristic genetic feature is the nonrandom gain of chromosomes X, 4, 6, 10, 14, 17, 18 and 21, with individual trisomies or tetrasomies being seen in over 75% of cases, but the pathogenesis remains poorly understood. We performed whole-genome sequencing (WGS) (n = 16) and/or whole-exome sequencing (WES) (n = 39) of diagnostic and remission samples from 51 cases of high hyperdiploid ALL to further define the genomic landscape of this malignancy. The majority of cases showed involvement of the RTK-RAS pathway and of histone modifiers. No recurrent fusion gene–forming rearrangement was found, and an analysis of mutations on trisomic chromosomes indicated that the chromosomal gains were early events, strengthening the notion that the high hyperdiploid pattern is the main driver event in this common pediatric malignancy.

Rip2 Deficiency Leads to Increased Atherosclerosis Despite Decreased Inflammation

Rationale: The innate immune system and in particular the pattern-recognition receptors Toll-like receptors have recently been linked to atherosclerosis. Consequently, inhibition of various signaling molecules downstream of the Toll-like receptors has been tested as a strategy to prevent progression of atherosclerosis. Receptor-interacting protein 2 (Rip2) is a serine/threonine kinase that is involved in multiple nuclear factor-&kgr;B (NF&kgr;B) activation pathways, including Toll-like receptors, and is therefore an interesting potential target for pharmaceutical intervention. Objective: We hypothesized that inhibition of Rip2 would protect against development of atherosclerosis. Methods and Results: Surprisingly, and contrary to our hypothesis, we found that mice transplanted with Rip2−/− bone marrow displayed markedly increased atherosclerotic lesions despite impaired local and systemic inflammation. Moreover, lipid uptake was increased whereas immune signaling was reduced in Rip2−/− macrophages. Further analysis in Rip2−/− macrophages showed that the lipid accumulation was scavenger-receptor independent and mediated by Toll-like receptor 4 (TLR4)–dependent lipid uptake. Conclusions: Our data show that lipid accumulation and inflammation are dissociated in the vessel wall in mice with Rip2−/− macrophages. These results for the first time identify Rip2 as a key regulator of cellular lipid metabolism and cardiovascular disease.

Increased lipolysis by secretory phospholipase A2 group V of lipoproteins in diabetic dyslipidaemia

Background.  Lipolysis of lipoproteins by secretory phospholipase A2 group V (sPLA2‐V) promotes inflammation, lipoprotein aggregation and foam cell formation – all considered as atherogenic mechanisms.

Prognostic implications of mutations in NOTCH1 and FBXW7 in childhood T-all treated according to the NOPHO ALL-1992 and ALL-2000 protocols

In children, T‐cell acute lymphoblastic leukemia (T‐ALL) has inferior prognosis compared with B‐cell precursor ALL. In order to improve survival, individualized treatment strategies and thus risk stratification algorithms are warranted, ideally already at the time of diagnosis.

LDL‐associated apolipoprotein J and lysozyme are associated with atherogenic properties of LDL found in type 2 diabetes and the metabolic syndrome

Pettersson C, Karlsson H, Ståhlman M, Larsson T, Fagerberg B, Lindahl M, Wiklund O, Borén J, Fogelstrand L (Institute of Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg; Linköping University, Linköping, Sweden) LDL‐associated apolipoprotein J and lysozyme are associated with atherogenic properties of LDL found in type 2 diabetes and the metabolic syndrome. J Intern Med 2010; 269: 306–321.

Residual disease detected by flow cytometry is an independent predictor of survival in childhood acute myeloid leukaemia; results of the NOPHO-AML 2004 study.

Early response after induction is a prognostic factor for disease outcome in childhood acute myeloid leukaemia (AML). Residual disease (RD) detection by multiparameter flow cytometry (MFC) was performed at day 15 and before consolidation therapy in 101 patients enrolled in the Nordic Society of Paediatric Haemato‐Oncology AML 2004 study. A multicentre laboratory approach to RD analysis was used. Event‐free survival (EFS) and overall survival (OS) was significantly different in patients with and without RD at both time points, using a 0·1% RD cut‐off level. RD‐negative and ‐positive patients after first induction showed a 5‐year EFS of 65 ± 7% and 22 ± 7%, respectively (P < 0·001) and an OS of 77 ± 6% (P = 0·025) and 51 ± 8%. RD‐negative and ‐positive patients at start of consolidation therapy had a 5‐year EFS of 57 ± 7% and 11 ± 7%, respectively (P < 0·001) and an OS of 78 ± 6% and 28 ± 11%) (P < 0·001). In multivariate analysis only RD was significantly correlated with survival. RD before consolidation therapy was the strongest independent prognostic factor for EFS [hazard ratio (HR):5·0; 95% confidence interval (CI):1·9–13·3] and OS (HR:7·0; 95%CI:2·0–24·5). In conclusion, RD before consolidation therapy identifies patients at high risk of relapse in need of intensified treatment. In addition, RD detection can be performed in a multicentre setting and can be implemented in future trials.

Patient-tailored analysis of minimal residual disease in acute myeloid leukemia using next-generation sequencing

Next‐generation sequencing techniques have revealed that leukemic cells in acute myeloid leukemia often are characterized by a limited number of somatic mutations. These mutations can be the basis for the detection of leukemic cells in follow‐up samples. The aim of this study was to identify leukemia‐specific mutations in cells from patients with acute myeloid leukemia and to use these mutations as markers for minimal residual disease. Leukemic cells and normal lymphocytes were simultaneously isolated at diagnosis from 17 patients with acute myeloid leukemia using fluorescence‐activated cell sorting. Exome sequencing of these cells identified 240 leukemia‐specific single nucleotide variations and 22 small insertions and deletions. Based on estimated allele frequencies and their accuracies, 191 of these mutations qualified as candidates for minimal residual disease analysis. Targeted deep sequencing with a significance threshold of 0.027% for single nucleotide variations and 0.006% for NPM1 type A mutation was developed for quantification of minimal residual disease. When tested on follow‐up samples from a patient with acute myeloid leukemia, targeted deep sequencing of single nucleotide variations as well as NPM1 was more sensitive than minimal residual disease quantification with multiparameter flow cytometry. In conclusion, we here describe how exome sequencing can be used for identification of leukemia‐specific mutations in samples already at diagnosis of acute myeloid leukemia. We also show that targeted deep sequencing of such mutations, including single nucleotide variations, can be used for high‐sensitivity quantification of minimal residual disease in a patient‐tailored manner.

Glucose impairs B‐1 cell function in diabetes

B‐1 lymphocytes produce natural immunoglobulin (Ig)M, among which a large proportion is directed against apoptotic cells and altered self‐antigens, such as modified low‐density lipoprotein (LDL). Thereby, natural IgM maintains homeostasis in the body and is also protective against atherosclerosis. Diabetic patients have an increased risk of developing certain infections as well as atherosclerosis compared with healthy subjects, but the underlying reason is not known. The aim of this study was to investigate whether diabetes and insulin resistance affects B‐1 lymphocytes and their production of natural IgM. We found that diabetic db/db mice had lower levels of peritoneal B‐1a cells in the steady state‐condition compared to controls. Also, activation of B‐1 cells with the Toll‐like receptor (TLR)‐4 agonist Kdo2‐Lipid A or immunization against Streptococcus pneumoniae led to a blunted IgM response in the diabetic db/db mice. In‐vitro experiments with isolated B‐1 cells showed that high concentrations of glucose, but not insulin or leptin, caused a reduced secretion of total IgM and copper‐oxidized (CuOx)‐LDL‐ and malondialdehyde (MDA)‐LDL‐specific IgM from B‐1 cells in addition to a decreased differentiation into antibody‐producing cells, proliferation arrest and increased apoptosis. These results suggest that metabolic regulation of B‐1 cells is of importance for the understanding of the role of this cell type in life‐style‐related conditions.