Suppressors Of Cytokine Signaling in G-CSF-induced neutrophil development

G-CSF is the most important growth factor involved in the production of neutrophilic granulocytes. Signaling routes activated upon ligand binding to the G-CSF receptor (G-CSF-R) control survival, proliferation and differentiation of myeloid progenitor cells towards mature neutrophils. Elucidation of the signaling pathways involved in this process is important for understanding normal neutrophil development and for better insights in diseases with perturbed neutrophil production such as neutropenia and myeloid leukemia. In Chapter 1 of this thesis an overview of the current knowledge on the G-CSF-R is given and the signaling pathways activated by G-CSF are introduced. Upon GCSF binding, kinases of the JAK and Src kinase families become active and the four tyrosines of the receptor, located at positions 704, 729, 744 and 764 are phosphorylated. Multiple signaling pathways are subsequently activated via recruitment of intermediates to these phosphorylated tyrosines as well as via tyrosine independent mechanisms. A well known signaling route activated by the G-CSF-R is the JAK-STAT pathway. The most prominent STATs that are activated by G-CSF are STAT3, implicated in mediating a cell cycle arrest, and STAT5, which contributes to proliferation and cell survival

G-CSF receptor truncations found in SCN/AML relieve SOCS3-controlled inhibition of STAT5 but leave suppression of STAT3 intact

Truncated granulocyte colony-stimulating factor receptors (G-CSF-Rs) are implicated in severe congenital neutropenia (SCN) and the consecutive development of acute myeloid leukemia (AML). Mice expressing G-CSF-R truncation mutants (gcsfr-d715) show defective receptor internalization, an increased signal transducer and activator of transcription 5 (STAT5)/STAT3 activation ratio, and hyperproliferative responses to G-CSF treatment. We determined whether a lack of negative feedback by suppressor of cytokine signaling (SOCS) proteins contributes to the signaling abnormalities of G-CSF-R-d715. Expression of SOCS3 transcripts in bone marrow cells from G-CSF-treated gcsfr-d715 mice was approximately 60% lower than in wild-type (WT) littermates. SOCS3 efficiently suppressed STAT3 and STAT5 activation by WT G-CSF-R in luciferase reporter assays. In contrast, while SOCS3 still inhibited STAT3 activation by G-CSF-R-d715, STAT5 activation was no longer affected. This was due mainly to loss of the SOCS3 recruitment site Tyr729, with an additional contribution of the internalization defects of G-CSF-R-d715. Because Tyr729 is also a docking site for the Src homology 2-containing protein tyrosine phosphatase-2 (SHP-2), which binds to and inactivates STAT5, we suggest a model in which reduced SOCS3 expression, combined with the loss of recruitment of both SOCS3 and SHP-2 to the activated receptor complex, determine the increased STAT5/STAT3 activation ratio and the resulting signaling abnormalities projected by truncated G-CSF-R mutants

Systemic Inflammation and Lung Function Impairment in Morbidly Obese Subjects with the Metabolic Syndrome

__Abstract__ __Background__: Obesity and asthma are associated. There is a relationship between lung function impairment and the metabolic syndrome. Whether this relationship also exists in the morbidly obese patients is still unknown. Hypothesis. Low-grade systemic inflammation associated with the metabolic syndrome causes inflammation in the lungs and, hence, lung function impairment. __Methods__: This is cross-sectional study of morbidly obese patients undergoing preoperative screening for bariatric surgery.Metabolic syndrome was assessed according to the revised NCEP-ATP III criteria. Results. A total of 452 patients were included. Patients with the metabolic syndrome ( = 293) had significantly higher blood monocyte (mean 5.3 versus 4.9, = 0.044) and eosinophil percentages (median 1.0 versus 0.8, = 0.002), while the total leukocyte count did not differ between the groups.The FEV1/FVC ratio was significantly lower in patients with the metabolic syndrome (76.7% versus 78.2%, = 0.032). Blood eosinophils were associated with FEV1/FVC ratio (adj. B −0.113, = 0.018). Conclusion. Although the difference in FEV1/FVC ratio between the groups is relatively small, in this cross-sectional study, and its clinical relevancemay be limited, these data indicate that the presence of the metabolic syndrome may influence lung function impairment, through the induction of relative eosinophilia

Contribution of Type 2 Diabetes Mellitus to Subclinical Atherosclerosis in Subjects with Morbid Obesity

Introduction: Type 2 diabetes mellitus (T2DM) and obesity are both related to increased risk of cardiovascular disease and mortality. Early atherosclerotic vascular changes can be detected by non-invasive tests like carotid artery intima-media thickness (cIMT) and pulse wave velocity (PWV). Both cIMT and PWV are significantly impaired in T2DM patients and in obese patients, but the additional effect of T2DM on these vascular measurements in obese subjects has not been evaluated. Methods: Two hundred morbidly obese patients with or without T2DM were enrolled in a prospective cohort study and underwent extensive laboratory testing, including cIMT and PWV measurements. The cohort was divided into a group with and a group without T2DM. Results: Within this cohort, 43 patients (21.5%) were diagnosed with T2DM. These patients were older and had more often (a history of) hypertension as compared to patients without T2DM. HbA1c levels were significantly increased, while LDL cholesterol was significantly lower and the use of statins higher than in non-diabetic participants. cIMT and PWV were significantly increased in subjects suffering from T2DM. The variability in cIMT and PWV was related to differences in age and systolic blood pressure, but not to the presence of T2DM. Conclusion: While T2DM negatively affects the vasculature in morbid obesity, hypertension and age seem to be the major risk factors, independent from the presence of T2DM. Clinical Trial Registration: Dutch Trial Register NTR5172

Erythrocyte-Bound Apolipoprotein B in Relation to Atherosclerosis, Serum Lipids and ABO Blood Group

Introduction:Erythrocytes carry apolipoprotein B on their membrane, but the determining factors of erythrocyte-bound apolipoprotein B (ery-apoB) are unknown. We aimed to explore the determinants of ery-apoB to gain more insight into potential mechanisms.Methods:Subjects with and without CVD were included (N = 398). Ery-apoB was measured on fresh whole blood samples using flow cytometry. Subjects with ery-apoB levels ≤0.20 a.u. were considered deficient. Carotid intima media thickness (CIMT) was determined as a measure of (subclinical) atherosclerosis.Results:Mean ery-apoB value was 23.2% lower in subjects with increased CIMT (0.80±0.09 mm, N = 140) compared to subjects with a normal CIMT (0.57±0.08 mm, N = 258) (P = 0.007, adjusted P<0.001). CIMT and ery-apoB were inversely correlated (Spearman's r: -0.116, P = 0.021). A total of 55 subjects (13.6%) were considered ery-apoB deficient, which was associated with a medical history of CVD (OR: 1.86, 95% CI 1.04-3.33; adjusted OR: 1.55; 95% CI 0.85-2.82). Discontinuation of statins in 54 subjects did not influence ery-apoB values despite a 58.4% increase in serum apolipoprotein B. Subjects with blood group O had significantly higher ery-apoB values (1.56±0.94 a.u.) when compared to subjects with blood group A (0.89±1.15 a.u), blood group B (0.73±0.1.12 a.u.) or blood group AB (0.69±0.69 a.u.) (P-ANOVA = 0.002).Conclusion:Absence or very low values of ery-apoB are associated with clinical and subclinical atherosclerosis. While serum apolipoprotein B is not associated with ery-apoB, the ABO blood group seems to be a significant determinant

Prevalence of c-KIT mutations in gonadoblastoma and dysgerminomas of patients with disorders of sex development (DSD) and ovarian dysgerminomas

Activating c-KIT mutations (exons 11 and 17) are found in 10-40% of testicular seminomas, the majority being missense point mutations (codon 816). Malignant ovarian dysgerminomas represent similar to 3% of all ovarian cancers in Western countries, resembling testicular seminomas, regarding chromosomal aberrations and c-KIT mutations. DSD patients with specific Y-sequences have an increased risk for Type II Germ Cell Tumor/Cancer, with gonadoblastoma as precursor progressing to dysgerminoma. Here we present analysis of c-KIT exon 8, 9, 11, 13 and 17, and PDGFRA exon 12, 14 and 18 by conventional sequencing together with mutational analysis of c-KIT codon 816 by a sensitive and specific LightCycler melting curve analysis, confirmed by sequencing. The results are combined with data on TSPY and OCT3/4 expression in a series of 16 DSD patients presenting with gonadoblastoma and dysgerminoma and 15 patients presenting pure ovarian dysgerminomas without DSD. c-KIT codon 816 mutations were detected in five out of the total of 31 cases (all found in pure ovarian dysgerminomas). A synonymous SNP (rs 5578615) was detected in two patients, one DSD patient (with bilateral disease) and one patient with dysgerminoma. Next to these, three codon N822K mutations were detected in the group of 15 pure ovarian dysgerminomas. In total activating c-KIT mutations were found in 53% of ovarian dysgerminomas without DSD. In the group of 16 DSD cases a N505I and D820E mutation was found in a single tumor of a patient with gonadoblastoma and dysgerminoma. No PDGFRA mutations were found. Positive OCT3/4 staining was present in all gonadoblastomas and dysgerminomas investigated, TSPY expression was only seen in the gonadoblastoma/dysgerminoma lesions of the 16 DSD patients. This data supports the existence of two distinct but parallel pathways in the development of dysgerminoma, in which mutational status of c-KIT might parallel the presence of TSPY

Association of cardiovascular risk factors with carotid intima media thickness in patients with rheumatoid arthritis with low disease activity compared to controls: A cross-sectional study

Objectives Rheumatoid arthritis (RA) has been identified as an independent cardiovascular risk factor. The importance of risk factors such as hypertension and hyperlipidemia in the generation of atherosclerosis in RA patients is unclear. This study analyzed clinical parameters associated with carotid intima media thickness (cIMT) in patients with RA. Methods Subjects with RA and healthy controls without RA, both without known cardiovascular disease, were included. Participants underwent a standard physical examination and laboratory measurements including a lipid profile. cIMT was measured semi-automatically by ultrasound. Results In total 243 RA patients and 117 controls were included. The median RA disease duration was 7 years (IQ

The effect of sex and menopause on carotid intima-media thickness and pulse wave velocity in morbid obesity

Background: Women are relatively protected from cardiovascular disease compared with men. Since morbid obesity is an independent risk factor for cardiovascular disease, the current study investigated whether the association between sex and cardiovascular risk factors and outcomes can be demonstrated in subjects suffering from morbid obesity. Materials and methods: Two hundred subjects enrolled in a study on cardiovascular risk factors in morbid obesity underwent extensive laboratory screening, carotid intima‐media thickness (cIMT) and pulse wave velocity (PWV) measurements. Gender differences were analysed using univariate and multivariable linear regression models. In addition, the effect of menopause on cIMT and PWV was analysed. Results of these models were reported as B coefficients with 95% confidence intervals. Results: The group consisted of 52 men and 148 women, with a mean age of 41 (±11.8) years and a mean body mass index (BMI) of 42.7 (±5.2) kg/m2 . Both, cIMT and PWV were significantly higher in men than in women, although the difference in cIMT disappeared after adjustment for covariables such as waist circumference, age, high‐density lipoprotein cholesterol and mean arterial pressure. PWV was associated with sex after adjustments for covariables in morbidly obese patients. Postmenopausal women had significantly increased cIMT and PWV when compared with premenopausal women. Conclusion: Sex differences in PWV persist in subjects suffering from morbid obesity. However, no difference was found in cIMT between morbidly obese men and women after adjustment for classic cardiovascular risk factors. Premenopausal morbidly obese women are protected for cardiovascular disease when compared with postmenopausal morbidly obese women

Prevalence of c-KIT Mutations in Gonadoblastoma and Dysgerminomas of Patients with Disorders of Sex Development (DSD) and Ovarian Dysgerminomas

Activating c-KIT mutations (exons 11 and 17) are found in 10-40% of testicular seminomas, the majority being missense point mutations (codon 816). Malignant ovarian dysgerminomas represent ~3% of all ovarian cancers in Western countries, resembling testicular seminomas, regarding chromosomal aberrations and c-KIT mutations. DSD patients with specific Y-sequences have an increased risk for Type II Germ Cell Tumor/Cancer, with gonadoblastoma as precursor progressing to dysgerminoma. Here we present analysis of c-KIT exon 8, 9, 11, 13 and 17, and PDGFRA exon 12, 14 and 18 by conventional sequencing together with mutational analysis of c-KIT codon 816 by a sensitive and specific LightCycler melting curve analysis, confirmed by sequencing. The results are combined with data on TSPY and OCT3/4 expression in a series of 16 DSD patients presenting with gonadoblastoma and dysgerminoma and 15 patients presenting pure ovarian dysgerminomas without DSD. c-KIT codon 816 mutations were detected in five out of the total of 31 cases (all found in pure ovarian dysgerminomas). A synonymous SNP (rs 5578615) was detected in two patients, one DSD patient (with bilateral disease) and one patient with dysgerminoma. Next to these, three codon N822K mutations were detected in the group of 15 pure ovarian dysgerminomas. In total activating c-KIT mutations were found in 53% of ovarian dysgerminomas without DSD. In the group of 16 DSD cases a N505I and D820E mutation was found in a single tumor of a patient with gonadoblastoma and dysgerminoma. No PDGFRA mutations were found. Positive OCT3/4 staining was present in all gonadoblastomas and dysgerminomas investigated, TSPY expression was only seen in the gonadoblastoma/dysgerminoma lesions of the 16 DSD patients. This data supports the existence of two distinct but parallel pathways in the development of dysgerminoma, in which mutational status of c-KIT might parallel the presence of TSPY