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Query: UMLS:C0002895 (sickle cell disease)
 11,747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of our study was to assess the cytokine profile of sickle cell disease (SCD) patients in steady state and in vaso-occlusive crisis (VOC). VOC has a complex nature, involving interactions between sickle red blood cells (RBC), the endothelium, and leucocytes. Endothelial damage due to recurrent adhesion of sickle RBCs may disrupt endothelial function, leading to altered cytokine release. It is therefore pertinent to study the cytokine profile of SCD patients in steady state and in crisis prior to exploring its contribution to vaso-occlusive manifestations, since it is believed that an altered balance of proinflammatory and anti-inflammatory cytokines plays an important role in painful crisis. Cytokines including IL-1beta, IL-2, IL-4, IL-6, IL-8, TNF-alpha, and IFN-gamma were measured by commercially available ELISA kits in SCD patients (n = 60); in steady state (n = 26) and in painful crisis (n = 34) and compared with nonanemic age- and sex-matched normal Omani controls (n = 20). SCD patients in crisis showed elevated levels of TNF-alpha (P < 0.092) and IL-6 (P < 0.024) when compared with steady state. It was also observed that SCD patients in steady state showed a significant elevation in IL-1beta (P < 0.04), IL-6 (P < 0.0001), and IFN-gamma (P < 0.02) as compared to normal subjects. It is thus evident that both type I and type II cytokines are significantly altered in SCD patients. In steady state, type II proinflammatory cytokines are elevated, whereas in crisis, an additional augmentation of type I cytokines occurs, with persistent elevation of type II cytokines, emphasizing the role of perturbed endothelium and activated monocytes in the pathophysiology of vaso-occlusion in sickle cell crisis.
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PMID:Cytokine profile of sickle cell disease in Oman. 1555 Dec 90

The placental-umbilical unit in sickle cell disease (SCD) pregnancy was used to explore hypoxia in vivo, an important factor in the pathophysiology of this disease. Gross examination and microscopic analysis of the placentas, taken immediately after delivery, indicate good concordance between maturity and term as controls, but higher frequency of vascular injuries such as excess syncytial knots, excess fibrin deposits, congestion and villous necroses. Unexpectedly, neither leukocyte recruitment nor alteration in extraplacental membrane was observed, suggesting the absence of inflammation. Additionally, interleukin (IL)-6 and IL-8 concentrations, measured by enzyme-linked immunosorbent assay (ELISA), were similar in the placental maternal blood from controls and SCD. There were also no significant differences found in IL-6 vein blood concentrations between controls and SCD, IL-8 being not detected. Immunostaining of umbilical vein endothelium in SCD pregnancies showed redistribution of PECAM-1 (CD31), von Willebrand factor (vWF), and P-selectin to the cell surface, controls exhibiting the classical pattern. Staining quantification indicated increases in vWF (+36.2%; P=.006) and vascular endothelial growth factor (VEGF) expression (+96.0%; P=.006) over control, but a reduction in endothelial nitric oxide synthase (eNOS) (-45.5%; P=.029). These results document, for the first time, direct functional adjustments in response to hypoxia in human in vivo. The mechanism for these changes has not been clearly established, but it may reflect increased tolerance to SCD hypoxic conditions and hypoxia in general.
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PMID:The placental-umbilical unit in sickle cell disease pregnancy: a model for studying in vivo functional adjustments to hypoxia in humans. 1566 92

A role for leukocytes in sickle cell vaso-occlusive crisis is becoming increasingly recognized. Neutrophil counts are higher in sickle cell patients and neutrophils from these patients demonstrate increased adhesion to endothelial monolayers under certain circumstances. The effects of selected cytokines on the adhesion mechanisms of normal neutrophils and neutrophils from sickle cell anaemia patients (SCA neutrophils) were investigated. Neutrophils were separated from the blood of homozygous (HbSS) SCA patients and healthy controls. Following pre-incubation (25 min, 37 degrees C) of the cells with cytokines, the adhesion of the cells to fibronectin (FN)-coated plates (20 micro) was determined (60 min, 37 degrees C, 5% CO2). Basal adhesion of normal and SCA neutrophils to FN was not statistically different. Pretreatment of normal neutrophils with either IL-6 (10-100 pg/ml), GCSF (1- 10 ng/ml) or IL-8 (1-100 ng/ml) had no significant effect upon their adhesion to FN. In contrast, SCA neutrophil adhesion to FN was increased significantly following pre-incubation with IL-6, G-CSF and IL-8 (p < 0.01). RANTES (1-100 ng/ml) had no significant effect on either normal or SCA neutrophil adhesion to FN. Flow-cytometric analyses demonstrated that IL-8 (10 ng/ml) significantly augments CD11b (Mac-1 integrin subunit) expression on SCA neutrophils, but not normal neutrophils. IL-6 and G-CSF (10 pg/ml and 10 ng/ml, respectively), however, had no effect on SCA neutrophil adhesion molecule expression. In conclusion, SCA neutrophil adhesion mechanisms may increase in the presence of certain cytokines, in vivo, and this activation may contribute to the physiopathology of sickle cell disease.
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PMID:Effect of cytokines and chemokines on sickle neutrophil adhesion to fibronectin. 1580 92

Tissue hypoxemia is common in several pathological diseases, including vaso-occlusion in sickle cell disease and myocardial infarction. One finds increased presence of leukocytes during lung injury and at sites of inflammation in vascular endothelium. In this study, we used human pulmonary microvascular endothelial cells and human dermal microvascular endothelial immortalized cell line to delineate the cellular signaling mechanism of hypoxia- and CoCl2 (a mimetic of hypoxia)-induced IL-8 expression, and the latter's role in chemotaxis of polmorphonuclear neutrophils. We show that hypoxia- and CoCl2-induced IL-8 mRNA and protein expression involved activation of PI3K/Akt and p38 MAPK, but not MEK kinase. Analysis of some transcription factors associated with IL-8 promoter revealed that hypoxia and CoCl2 increased DNA-binding activity of hypoxia-inducible factor-1alpha (HIF-1alpha), NF-kappaB, and AP-1. In addition, we show that hypoxia- and CoCl2-induced IL-8 expression requires activation of HIF as demonstrated by the following: 1) EMSA; 2) transfection studies with IL-8 promoter reporter constructs with mutation in HIF-1alpha binding site; 3) attenuation of IL-8 expression by both HIF-1alpha small interfering RNA and R59949; 4) augmentation of IL-8 expression by either transfection with HIF-prolyl hydroxylase-2 small interfering RNA or overexpression of HIF-1alpha; and 5) chromatin immunoprecipitation analysis. Moreover, conditioned medium from hypoxia-treated endothelial cells augmented chemotaxis of neutrophils, due to release of IL-8. These data indicate that hypoxia-induced signaling in vascular endothelium for transcriptional activation of IL-8 involves PI3K/Akt, p38 MAPK, and HIF-1alpha. Pharmacological agents, which inhibit HIF-1alpha, may possibly ameliorate inflammation associated with hypoxia in pathological diseases.
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PMID:A novel role of hypoxia-inducible factor in cobalt chloride- and hypoxia-mediated expression of IL-8 chemokine in human endothelial cells. 1740 46

Sickle cell anemia (HbSS) is characterized by hypermetabolism, chronic inflammation, and increased oxidative stress, but the relationship between these factors is undefined. In this study, we examined indicators of inflammatory process and markers of oxidative damage and their impact on resting energy expenditure (REE) in stable HbSS adolescents (n = 35) and healthy controls carrying normal hemoglobin genotype (HbAA) (n = 39). C-reactive protein (CRP), white blood cell (WBC) count, and proinflammatory cytokines were measured as markers of inflammation and 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (F2-IsoPM) as a marker of oxidative stress. REE was measured by indirect calorimetry. WBC counts (11.90 +/- 5.3 x10/muL versus 5.6 +/- 1.9 x10/muL; p < 0.001), serum CRP (9.1 +/- 11.0 mug/mL versus 0.4 +/- 0.7 mug/mL; p < 0.001) and serum IL-8 (7.5 +/- 4.4 pg/mL versus 5.5 +/- 4.8 pg/mL; p = 0.011) were higher in HbSS than HbAA, suggesting an anti-inflammatory response in HbSS. Higher urinary F2-IsoPM in HbSS (1.2 +/- 0.4 versus 0.7 +/- 0.3 ng/mg creatinine; p < 0.001) indicates increased oxidative stress. Fat free mass (FFM), hemoglobin (Hgb), interleukin (IL)-8, and F2-IsoPM were independent predictors of REE in HbSS (overall r = 0.778; p < 0.001). Low-grade inflammation and increased oxidative stress are present in adolescents with HbSS in the absence of acute crisis, and their markers are correlated with elevated REE.
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PMID:Energy expenditure, inflammation, and oxidative stress in steady-state adolescents with sickle cell anemia. 1723 28

The significance of the leukocyte in sickle cell disease (SCD) pathophysiology is becoming increasingly recognised; we sought to examine whether the chemotactic properties of neutrophils of SCD individuals may be altered and, further, to better understand the signalling events that mediate altered SCD neutrophil function. Adhesion to immobilised fibronectin (FN) and chemotaxis of control and SCD neutrophils were assessed using in vitro static adhesion assays and 96-well chemotaxis chamber assays. Adhesion assays confirmed a significantly higher basal adhesion of SCD neutrophils to FN, compared with control neutrophils. Chemotaxis assays established, for the first time, that SCD neutrophils demonstrate greater spontaneous migration and, also, augmented migration in response to IL-8, when compared with control neutrophils. Co-incubation of SCD neutrophils with KT5720 (an inhibitor of PKA) abrogated increased basal SCD neutrophil adhesion, spontaneous chemotaxis and IL-8-stimulated chemotaxis. Stimulation of SCD neutrophils with IL-8 also significantly augmented SCD neutrophil adhesion to FN with a concomitant increase in cAMP levels and this increase in adhesion was abolished by KT5720. Interestingly, the adhesive properties of neutrophils from SCD individuals on hydroxyurea therapy were not significantly altered and results indicate that a reduction in intracellular cAMP may contribute to lower the adhesive properties of these cells. Data indicate that up-regulated cAMP signalling plays a significant role in the altered adhesive and migratory properties in SCD neutrophils. Such alterations may have important implications for the pathophysiology of the disease and the cAMP-PKA pathway may represent a therapeutic target for the abrogation of altered leukocyte function.
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PMID:Role for cAMP-protein kinase A signalling in augmented neutrophil adhesion and chemotaxis in sickle cell disease. 1768 Aug 13

Pulmonary hypertension (PHT) develops in sickle cell disease (SCD) and is associated with high mortality. We previously showed that erythroid cells produce placenta growth factor (PlGF), which activates monocytes to induce proinflammatory cytochemokines, contributing to the baseline inflammation and severity in SCD. In this study, we observed that PlGF increased expression of endothelin-1 (ET-1) and endothelin-B receptor (ET-BR) from human pulmonary microvascular endothelial cells (HPMVECs) and monocytes, respectively. PlGF-mediated ET-1 and ET-BR expression occurred via activation of PI-3 kinase, reactive oxygen species and hypoxia inducible factor-1 alpha (HIF-1 alpha). PlGF increased binding of HIF-1 alpha to the ET-1 and ET-BR promoters; this effect was abrogated with mutation of hypoxia response elements in the promoter regions and HIF-1 alpha siRNA and confirmed by chromatin immunoprecipitation analysis. Furthermore, PlGF-mediated ET-1 release from HPMVECs and ET-BR expression in monocytes creates a PlGF-ET-1-ET-BR loop, leading to increased expression of MCP-1 and IL-8. Our studies show that PlGF-induced expression of the potent vasoconstrictor ET-1 and its cognate ET-BR receptor occur via activation of HIF-1 alpha, independent of hypoxia. PlGF levels are intrinsically elevated from the increased red cell turnover in SCD and in other chronic anemia (eg, thalassemia) and may contribute to inflammation and PHT seen in these diseases.
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PMID:Placenta growth factor augments endothelin-1 and endothelin-B receptor expression via hypoxia-inducible factor-1 alpha. 1865 Apr 59

Endothelial lipotoxicity has been implicated in the pathogenesis of multiple stages of cardiovascular disease from early endothelial dysfunction to manifest atherosclerosis and its complications. Saturated free fatty acids are the major inducers of endothelial cell apoptosis and inflammatory cytokines. In humans, the enzyme human stearoyl-CoA desaturase-1 (hSCD-1) is the limiting step of the desaturation of saturated to monounsaturated fatty acids. Since we could demonstrate the expression of SCD-1 in primary human arterial endothelial cells (HAECs), we aimed to prove a beneficial role of upregulated hSCD-1 expression. In contrast to other cells that are less susceptible to lipotoxicity, hSCD-1 was not upregulated in HAECs upon palmitate treatment. Following that, we could show that upregulation of hSCD-1 using the LXR activator TO-901317 in HAECs protects the cells against palmitate-induced lipotoxicity, cell apoptosis, and expression of inflammatory cytokines IL-6 and IL-8. Increased hSCD-1 activity was determined as increased C16:1/16:0 ratio and enhanced triglyceride storage in palmitate treated cells. The beneficial effect was clearly attributed to enhanced hSCD-1 activity. Overexpression of hSCD-1 blocked palmitate-induced cytotoxicity, and knockdown of hSCD-1 using siRNA abolished the protective effect of TO-901317 in HEK-293 cells. Additionally, inhibition of hSCD-1 with 10/12 CLA blocked the effect of TO-901317 on palmitate-induced lipotoxicity, cell apoptosis, and inflammatory cytokine induction in HAECs. We conclude that upregulation of hSCD-1 leads to a desaturation of saturated fatty acids and facilitates their esterification and storage, thereby preventing downstream effects of lipotoxicity in HAECs. These findings add a novel aspect to the atheroprotective actions of LXR activators in cardiovascular disease.
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PMID:Induction of stearoyl-CoA desaturase protects human arterial endothelial cells against lipotoxicity. 1852 27

Inflammation, cell adhesion to vascular endothelium, and endothelial injury contribute to sickle cell anemia (SCA) vaso-occlusion. Although alterations in inflammatory cytokines and biomarkers have been related, reports have been conflicting, and a conclusive role for these molecules in the disease remains to be established. Furthermore, the effect of hydroxyurea therapy (HU) on the release of inflammatory mediators is not understood. This study aimed to determine plasma levels and leukocyte gene expressions of inflammatory mediators in healthy controls, steady-state SCA patients, and SCA patients on HU therapy. TNF-alpha, IL-8, and PGE(2) levels were significantly higher in the plasma of SCA individuals when compared with control individuals. HU therapy was associated with a significant reversal of augmented TNF-alpha and, interestingly, increased plasma anti-inflammatory IL-10. IFN-gamma, IL-10, cyclooxygenase 2 (COX-2), and inducible NO synthase (iNOS) gene expressions were unaltered in SCA mononuclear cells (MC); however, gene expressions of TNF-alpha, IL-8, and the protective enzyme heme oxygenase-1 (HO-1) were significantly higher. HU therapy was not associated with significantly altered SCA MC inflammatory gene expression, although COX-2 mRNA expression was decreased. In SCA neutrophils, gene expressions of IL-8, IFN-gamma, iNOS, and HO-1 were significantly higher than those of control subjects. Patients on HU demonstrated lower iNOS and higher IL-10 neutrophil gene expressions. Taken together, data suggest that alterations in the gene expressions and productions of a number of pro- and anti-inflammatory mediators are present in SCA and importantly, in those patients on HU therapy. Knowledge of these pathways may contribute to further the understanding of the pathophysiology of this disease.
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PMID:Altered levels of cytokines and inflammatory mediators in plasma and leukocytes of sickle cell anemia patients and effects of hydroxyurea therapy. 1900 88

Since inflammation plays a prominent role in the pathogenesis of sickle cell anemia (SCA) and Duffy antigen receptor for chemokines (DARC) modulates the function of inflammatory processes, we analyzed the relationship between the erythrocyte DARC phenotype and clinical expression of SCA. DARC locus was genotyped in 212 SS adult patients followed by the sickle cell center of Guadeloupe (French West Indies). After patients' stratification according to RBC DARC expression, the prevalence of renal disease, leg ulcers, priapism and osteonecrosis was compared between patient groups as well as hematological variables and plasma levels of chemokines. Duffy-positive patients exhibited higher counts of white blood cells (9.95+/-2.36 vs 8.88+/-2.32 10(9)/L, p=0.0066), polynuclear neutrophils (5.1+/-1.73 vs 4.51+/-1.71 10(9)/L, p=0.0227), higher plasma levels of IL-8 (4.46+/-1.22 vs 1.47+/-0.5 pg/mL, p=0.0202) and RANTES (27.8+/-4.3 vs 18.1+/-2.3 ng/mL, p=0.04) than Duffy-negative patients. No association was detected between RBC expression of DARC and the studied complications.
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PMID:Association between Duffy antigen receptor for chemokines expression and levels of inflammation markers in sickle cell anemia patients. 2063 42


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