Plasma and erythrocyte lipids in hereditary spherocytosis

Association of pro-inflammatory high-density lipoprotein cholesterol with clinical and laboratory variables in sickle cell disease

Background Although cholesterol levels are known to be decreased in sickle cell disease (SCD), the level of pro-inflammatory high-density lipoprotein cholesterol (proHDL) and its association with clinical complications and laboratory variables has not been evaluated. Design and methods Plasma levels of total cholesterol, high-density lipoprotein cholesterol (HDL), proHDL, and selected clinical and laboratory variables were ascertained in a cohort of SCD patients and healthy African American control subjects in this single-center, cross-sectional study. Results Although total cholesterol was significantly lower in SCD patients compared with control subjects, HDL and proHDL levels were similar in both the SCD and control groups. In univariate analyses, proHDL was correlated with echocardiography-derived tricuspid regurgitant jet velocity. ProHDL was higher in SCD patients with suspected pulmonary hypertension (PHT) compared to patients without suspected PHT. ProHDL was positively correlated with lactate dehydrogenase, total bilirubin, direct bilirubin, indirect bilirubin, prothrombin fragment 1+2, D-dimer, and thrombin-antithrombin complexes. In multivariable analyses, only higher lactate dehydrogenase and direct bilirubin levels were associated with higher levels of proHDL. Conclusions SCD is characterized by hypocholesterolemia. Although proHDL is not increased in SCD patients compared with healthy controls, it is significantly associated with markers of liver disease. In addition, proHDL is associated with tricuspid regurgitant jet velocity and markers of coagulation, although these associations are not significant in multivariable analyses.

Serum lipids and lipoproteins in malaria--a systematic review and meta-analysis

BACKGROUND

Serum lipid profile changes have been observed during malaria infection. The underlying biological mechanisms remain unclear. The aim of this paper is to provide an overview on those serum lipid profile changes, and to discuss possible underlying biological mechanisms and the role of lipids in malaria pathogenesis.

METHODS

A systematic review and meta-analysis to determine lipid profile changes during malaria was conducted, following PRISMA guidelines. Without language restrictions, Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus were searched for studies published up to 11 July, 2013, that measured serum lipid parameters in malaria patients. Also, major trial registries were searched. Mean differences in lipid profile parameters were combined in fixed and random effects meta-analysis, with a separate analysis for different groups of controls (healthy, other febrile illnesses or very low parasitaemia). These parameters were also compared between severe malaria and uncomplicated malaria. Funnel plots were used to test for publication bias.

RESULTS

Of 2,518 studies reviewed, 42 met the criteria for inclusion in the qualitative analysis, and of these, 15 reported the necessary data for inclusion in the meta-analysis for cholesterol; nine for high-density lipoprotein (HDL), eight for low-density lipoprotein (LDL), and nine for triglycerides, respectively. Total cholesterol, HDL and LDL concentrations were lower in malaria and other febrile diseases compared to healthy controls. The decline was more pronounced and statistically significant during malaria compared to other febrile diseases. These results were consistent across included studies. Triglycerides were raised compared to healthy controls, but not statistically significant when compared to symptomatic controls.

CONCLUSIONS

This meta-analysis suggests that the observed lipid profile changes are characteristic for malaria. Although a definite link with the pathogenesis of malaria cannot yet be demonstrated, plausible hypotheses of biological mechanisms involving host lipid alterations and the pathogenesis of malaria exist. An increased research effort to elucidate the precise pathways is warranted, since this could lead to better understanding of malaria pathophysiology and consequently to novel treatment approaches.

Hypocholesterolemia is associated negatively with hemolysate lipid peroxidation in sickle cell anemia patients

The oxidative stress levels in plasma and hemolysate and cholesterol levels in plasma of sickle cell anemia patients, carriers and controls were evaluated. A total of 40 cases-17 patients, 13 carriers and 10 controls-were involved in the study. Plasma and hemolysate malondialdehyde (MDA) were detected via thiobarbituric acid reaction with a fluorimetric detector by high-performance liquid chromatography system. Plasma cholesterol was determined by enzymatic colorimetric method. Mean MDA levels of SCA patients were higher than those of the carriers' and healthy children's both in plasma and in hemolysate (P < 0.005). The mean plasma and hemolysate MDA levels were 25.3 ± 1.6 nmol/l and 86.7 ± 19.3 nmol/l in patients, 19.1 ± 0.8 nmol/l and 54.1 ± 10.8 nmol/l in carriers and 19.6 ± 0.8 nmol/l and 56.8 ± 9.3 nmol/l in healthy children. Mean plasma total cholesterol levels were 92.1 ± 19.1 mg/dl in patients, 116.2 ± 23.3 mg/dl in carriers and 126.6 ± 16.4 mg/dl in controls (P < 0.005). There was a significant negative correlation of -0.520 between hemolysate MDA and plasma cholesterol levels in patients (P < 0.05). The degree of correlation increased up to -0.782 (P = 0.008) in the patients with HbSS phenotype. This negative correlation between MDA and cholesterol may imply a potential association between oxidative stress and hypocholesterolemia in sickle cell anemia.

Vascular complications after splenectomy for hematologic disorders

The most widely recognized long-term risk of splenectomy is overwhelming bacterial infection. More recently, thrombosis has become appreciated as another potential complication of the procedure. Because of these long-term risks, the indications for and timing of splenectomy are debated in the medical community. Accordingly, the adverse effects and benefits of splenectomy for hematologic disorders and other conditions demand further study. This comprehensive review summarizes the existing literature pertaining to vascular complications after splenectomy for hematologic conditions and attempts to define the potential pathophysiologic mechanisms involved. This complex topic encompasses diverse underlying conditions for which splenectomy is performed, diverse thrombotic complications, and multiple pathophysiologic mechanisms.

Dural venous thrombosis following splenectomy in a patient with hereditary spherocytosis

Hereditary spherocytosis is a common form of hemolytic anemia sometimes requiring splenectomy in recalcitrant cases. The complications of splenectomy include an increased risk of thrombosis, usually presenting with deep vein thrombosis or pulmonary embolism. However, common complaints such as headache should warn clinicians of involvement in less common sites, primarily the dural venous system. The case of dural venous thrombosis in a patient with hereditary spherocytosis and splenectomy is discussed. The potential mechanisms associated with thrombosis formation in this population and its treatment are discussed.

Laboratory markers of thrombosis risk in children with hereditary spherocytosis

BACKGROUND

Recent data suggest that adults with hereditary spherocytosis (HS) may be protected from atherothrombosis before splenectomy but have increased risk of thrombosis following splenectomy. In order to aid in making informed decisions regarding splenectomy in children with HS, we conducted a retrospective study of several surrogate laboratory markers of thrombosis risk in children with HS.

METHODS

A retrospective record review was performed on 246 children with HS. Platelet count and hemoglobin concentration were recorded prior to and following splenectomy in each patient. Serum cholesterol levels were collected from the record when available.

RESULTS

Prior to splenectomy, hypocholesterolemia was common. Mean platelet counts in 31 evaluable patients pre- and post-splenectomy were 334 and 608 x 10(9)/L, respectively (P < 0.001). Twenty-nine patients (94%) exhibited persistent thrombocytosis following splenectomy. Hemoglobin values following splenectomy often rose to higher than age and gender-matched norms, with 30% of measurements greater than the 90th percentile and 17% greater than the 97th percentile.

CONCLUSIONS

The findings of hypocholesterolemia before splenectomy and thrombocytosis and mild polycythemia afterwards support the hypothesis that patients with HS might be protected from thrombosis before splenectomy and/or more susceptible afterwards. Prospective studies of additional prothrombotic biomarkers and thrombotic events in HS patients are warranted.

Hypocholesterolemia in chronic anemias with increased erythropoietic activity

Hypocholesterolemia of unknown etiology has been previously described in various chronic anemias. Few small studies also suggested that those patients have a lower incidence of atherosclerotic events. The aim of our study was to determine the extent of hypocholesterolemia in various types of anemias. We studied 59 patients with chronic anemias associated with high-erythropoietic activity (thalassemia intermedia, congenital dyserythropoietic anemia type I, congenital spherocytosis), 8 patients with low-erythropoietic activity anemias (acquired aplastic anemia, Fanconi anemia, and Diamond Blackfan anemia), and 20 healthy controls. Mean serum cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, hemoglobin, serum ferritin, soluble transferrin receptor (STR), and serum erythropoietin levels were determined in each patient. All patients with chronic anemia and increased erythropoietic activity had hypocholesterolemia, whereas none of those with low erythropoietic activity was hypocholesterolemic. Mean serum cholesterol, HDL cholesterol, and LDL cholesterol levels were found to be significantly lower in the high-erythropoietic activity group (80+/-19 mg/dl; 31+/-10 mg/dl; 35+/-14 mg/dl, respectively) compared with the control group (P<0.001; 0.001; 0.001, respectively) and the low-erythropoietic activity group (P<0.001; 0.001; 0.01, respectively). Significant inverse correlation (R2=0.507) was observed between serum cholesterol and STR levels, which in the absence of iron deficiency reflect bone marrow activity. Taken together, our results imply that hypocholesterolemia accompanies anemias with high-erythropoietic activity. We suggest that the high-erythropoitic activity-associated hypocholesterolemia is due to increased cholesterol requirements by the proliferating erythoid cells. Further studies are needed to elucidate the exact mechanism and the possible clinical consequences of this phenomenon.

Ca2+ influx in normal and spherocytic red cells

The influx of 45Ca2+ into normal red cells and various types of spherocytic red cells was studied after blocking active Ca2+ extrusion by vanadate. The measurements were performed with and without verapamil, a calcium antagonist. The influx of Ca2+ into red cells from unsplenectomized persons was 22 +/- 7 mumol/l packed red cells/h (mean +/- SD), and 17 +/- 7 mumol/l per h when incubated with verapamil. The influx of Ca2+ into red cells from four splenectomized normal controls was of the same magnitude as in the unsplenectomized controls but there was no effect of verapamil on the influx rate. The influx of Ca2+ into red cells from nine splenectomized patients with hereditary spherocytosis (HS) was 27 +/- 9 mumol/l per h without and 24 +/- 9 mumol/l per h with verapamil. In 9 normal red cell samples made spherocytic by thermal damage the corresponding values were 32 +/- 16 and 31 +/- 19 mumol/l per h, respectively. The uptake of Ca2+ in chlorpromazine-induced spherocytic red cells was 20 +/- 4 mumol/l per h without and 19 +/- 5 mumol/l per h with verapamil in 9 experiments. These results indicate that although in HS erythrocytes changes in the cell membrane lead to an increased Ca2+ influx, the slow calcium channels are not affected, whereas in spherocytes induced by thermal damage or by incubation with chlorpromazine the channels are blocked, at least partly.

Thrombocyte aggregation in hereditary spherocytosis

Thrombocyte function was studied in seven splenectomized patients and one unsplenectomized patient with hereditary or congenital spherocytosis (HS). Adenosine diphosphate (ADP) concentrations, which trigger the aggregation of control thrombocytes, induced only a release reaction in thrombocytes from six of the HS patients. Collagen-induced thrombocyte aggregation was also diminished in two patients, and epinephrine-induced thrombocyte aggregation in one patient. Two patients whose thrombocytes responded normally to ADP, collagen and epinephrine, were identical twins with spherocytosis of equivocal hereditary. Ristocetin-induced aggregation was normal in all the patients studied. Xanthines (pentoxifylline, theophylline) had no effect on the aggregation of thrombocytes from HS patients or controls. Half-life of thrombocytes was normal in the two splenectomized patients studied. The results demonstrate that not only red cells but also thrombocytes are defective in HS.