Sickle cell disease (SCD) consists of a group of hemoglobinopathies in which individuals present highly variable clinical manifestations. Sickle cell anemia (SCA) is the most severe form, while SC hemoglobinopathy (HbSC) is thought to be milder. Thus, we investigated the clinical manifestations and laboratory parameters by comparing each SCD genotype. We designed a cross-sectional study including 126 SCA individuals and 55 HbSC individuals in steady-state. Hematological, biochemical and inflammatory characterization was performed as well as investigation of previous history of clinical events. SCA patients exhibited most prominent anemia, hemolysis, leukocytosis and inflammation, whereas HbSC patients had increased lipid determinations. The main cause of hospitalization was pain crises on both genotypes. Vaso-occlusive events and pain crises were associated with hematological, inflammatory and anemia biomarkers on both groups. Cluster analysis reveals hematological, inflammatory, hemolytic, endothelial dysfunction and anemia biomarkers in HbSC disease as well as SCA. The results found herein corroborate with previous studies suggesting that SCA and HbSC, although may be similar from the genetic point of view, exhibit different clinical manifestations and laboratory alterations which are useful to monitor the clinical course of each genotype.

Hemolysis triggers the onset of several clinical manifestations of sickle cell anemia (SCA). During hemolysis, heme, which is derived from hemoglobin (Hb), accumulates due to the inability of detoxification systems to scavenge sufficiently. Heme exerts multiple harmful effects, including leukocyte activation and migration, enhanced adhesion molecule expression by endothelial cells and the production of pro-oxidant molecules. Area covered: In this review, we describe the effects of heme on leukocytes and endothelial cells, as well as the features of vascular endothelial cells related to vaso-occlusion in SCA. Expert commentary: Free Hb, heme and iron, potent cytotoxic intravascular molecules released during hemolysis, can exacerbate, modulate and maintain the inflammatory response, a main feature of SCA. Endothelial cells in the vascular environment, as well as leukocytes, can become activated via the molecular signaling effects of heme. Due to the hemolytic nature of SCA, hemolysis represents an interesting therapeutic target for heme-scavenging purposes.

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Introduction. Clinical complications in sickle cell anemia (SCA) are heterogeneous and involve several molecules. It has been suggested that SCA individuals present a dyslipidemic phenotype and that lipid parameters are associated with severe clinical complications, such as pulmonary hypertension. We sought to investigate associations between lipid parameters and clinical manifestations, as well as other laboratory parameters in a population of pediatric SCA patients. Methods. Our cross-sectional evaluation included 126 SCA patients in steady state and who were not undergoing lipid-lowering therapy. Hematological and biochemical parameters were characterized, and previous clinical manifestations were investigated. Results. Total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels were increased in patients with a previous history of pneumonia, which also positively correlated with HbS levels. Decreased LDL-C levels were also associated with leg ulcers and anemia. Elevated high-density lipoprotein cholesterol (HDL-C) levels were associated with pain crises, increased viscosity, and decreased hemolysis. Several studies have determined that lipids play a role in the vascular impairment seen in SCA, which was corroborated by our findings. Conclusions. In sum, our results suggest that total cholesterol, HDL-C, and LDL-C levels are associated with hemolysis and anemia markers and, most importantly, with clinical complications related to vasculopathy in SCA.

This study investigated the effects of hydroxyurea (HU) on hematological, biochemical and inflammatory parameters in children with sickle cell anemia (SCA) in association with β S haplotype and α-thalassemia. We included 22 children with SCA who were followed for an average of 14.5 months. Laboratory parameters were assessed by electronic methods, and molecular analysis was investigated by PCR-RFLP and allele-specific PCR. Results showed significant increases in hemoglobin, HbF, hematocrit, MCV, MCH, glucose, HDL-C and albumin levels, as well as significant decreases in MCHC and AST levels, WBC, neutrophils, eosinophils, lymphocytes and reticulocytes, in children during HU therapy. HbF levels were positively correlated with hemoglobin, hematocrit, MCV and total protein, yet negatively correlated with MCHC, RDW, AAT and AST during HU therapy ( p <0.05). Children who carried the Central African Republic haplotype, in response to HU therapy, presented significant increases in hemoglobin, hematocrit, triglycerides and uric acid levels, as well as significant decreases in MCHC, AST and direct bilirubin levels, WBC, neutrophils, eosinophils, lymphocytes and reticulocytes. Those with the Benin haplotype presented increases in HbF and albumin levels, and a reduction in platelet counts ( p <0.05). Children with α-thalassemia presented decreased ALT during HU use, while those without this deletion presented increases in hemoglobin, hematocrit, MCV, MCH, HDL-C and albumin, as well as decreases in MCHC, neutrophils, lymphocytes, reticulocytes and AST ( p <0.05). Hence, regardless of its use in association with β S haplotypes or α-thalassemia, HU seems to be linked to alterations in hemolytic, inflammatory, hepatic, lipid and glycemic profiles.

Alpha-1 antitrypsin (AAT) is an inhibitor of neutrophil elastase and a member of the serine proteinase inhibitor (serpin) superfamily, and little is known about its activity in sickle cell disease (SCD). We hypothesize that AAT may undergo changes in SCD because of the high oxidative stress and inflammation associated with the disease. We have found high AAT levels in SCD patients compared to controls, while mutant genotypes of SERPINA1 gene had decreased AAT levels, in both groups. AAT showed negative correlation with red blood cells, hemoglobin (Hb), hematocrit, high-density lipoprotein cholesterol, urea, creatinine, and albumin and was positively correlated with mean corpuscular Hb concentration, white blood cells, neutrophils, Hb S, bilirubin, lactate dehydrogenase, ferritin, and C-reactive protein. Patients with higher levels of AAT had more infection episodes (OR = 1.71, CI: 1.05–2.65, p = 0.02), gallstones (OR = 1.75, CI: 1.03–2.97, p = 0.02), and had more blood transfusions (OR = 2.35, CI: 1.51–3.65, p = 0.0001). Our data on AAT association with laboratory indices of hemolysis and inflammation suggest that it may be positively associated with SCD severity; the negative correlations with renal parameters suggest a cytoprotective mechanism in SCD patients. In summary, AAT may need to be included in studies related to SCD and in the discussion of further therapeutic strategies.

Reference values for cerebral blood flow velocity (CBFV) in hemoglobin SC disease (HbSC) have not been established. We aimed to investigate associations between laboratory and genetic biomarkers associated with CBFV in HbSC children. Sixty-eight HbSC children were included; CBFV was analyzed by transcranial Doppler, and the time-averaged maximum mean velocity (TAMMV) was estimated. Hematological, biochemical, immunological, and genetic analyses were performed. TAMMV was negatively correlated with red blood cell count (RBC) count, hemoglobin, hematocrit, and direct bilirubin (DB), yet positively correlated with monocytes and ferritin. We found that children with TAMMV ≥ 128 cm/s had decreased red blood cell distribution width (RDW) and nitric oxide metabolite (NOx) concentration. Children with TAMMV ≥ 143.50 cm/s had decreased hemoglobin and hematocrit, as well as increased ferritin levels. Decreased hemoglobin, hematocrit, RDW, and NOx and increased ferritin were detected in children with TAMMV ≥ 125.75 cm/s. The CAR haplotype was associated with higher TAMMV. In association analyses, RBC, hemoglobin, hematocrit, RDW, monocyte, DB, NOx, and ferritin, as well as the CAR haplotype, were found to be associated with higher TAMMV in HbSC children. Multivariate analysis suggested that high TAMMV was independently associated with hematocrit, RDW, and NOx. Additional studies are warranted to validate the establishment of a cutoff value of 125.75 cm/s associated with elevated TAMMV in HbSC children.

INTRODUCTION: Hemolysis is a hallmark of sickle cell disease (SCD) pathogenesis, with the release of hemoglobin (Hb) and heme into the plasma that can promote vasculopathy, inflammation, thrombosis, and renal injury. Plasma haptoglobin (Hp) and hemopexin (Hpx) tightly bind free Hb and heme, respectively, thwarting these clinical sequelae. Hp-Hb and Hpx-heme complexes bind to CD163 and CD91 receptors found primarily on macrophages and hepatocytes, respectively, and are taken up by receptor-mediated endocytosis. In SCD patients it is generally believed that chronic hemolysis depletes plasma haptoglobin and hemopexin levels, however we found only one paper in the literature that has reported plasma Hp and Hpx levels in SCD patients, albeit in a limited number of SS (n=5) and SC (n=3) patients (Muller-Eberhard U et al. Blood 1968). Here we report serum Hp and Hpx levels in 272 Brazilian SS, SC, and AA children along with systemic biomarkers of hemolysis, iron metabolism, inflammation leukocyte and platelet counts, and lipid metabolism. We hypothesize that serum Hp and Hpx levels will be significantly lower and biomarkers of hemolysis, iron metabolism, and inflammation will be significantly higher in SS and SC children compared to AA children. METHODS: The present study used blood samples collected prospectively from 272 unrelated steady-state SCD children with SS (n=179) and SC (n=93) disease. Patients were followed at Bahia Pediatrics Centers, during January 2010 to November 2015. The study included 28 healthy AA volunteers randomly selected from the Clinical Laboratory of the Faculdade de Farmácia da Universidade Federal da Bahia. The study was approved by the Fundação de Pesquisa Oswaldo Cruz research board, and all procedures were in accordance with the Declaration of Helsinki of 1975, as revised in 2000. Biochemical and inflammatory analyses were performed by immunochemistry assay and immunoassay. Hematological analyses were carried out using an electronic cell counter and the Hb profile was investigated by high performance liquid chromatography. Serum Hp and Hpx levels were measured by enzyme-linked immunoassay following the manufacturer's instructions. RESULTS: Evaluating the Hp and Hpx levels, we found that SS and SC patients have lower Hp and Hpx levels (SS<SC<AA) than AA controls (p<.001, Table 1). Similarly, SS and SC patients have lower hemoglobin and hematocrits (SS<SC<AA) and increased reticulocyte counts and serum LDH (SS>SC>AA) than AA controls (p<.001, Table 1). Total, direct, and indirect bilirubin, markers of heme degradation, followed a similar pattern (SS>SC>AA, p<.001, Table 1). These data may reflect more intravascular hemolysis in the following pattern: SS>SC>AA. Likewise, serum ferritin levels, a marker of body iron stores, were higher in SS and SC patients than AA controls (SS>SC>AA, p<.001, Table 1). CRP levels and white blood cells count, markers of inflammation, also reflected the same pattern (SS>SC>AA, p<.001, Table 1). In a different pattern, platelet counts were highest in SS patients and lowest in SC patients (SS>AA>SC). Finally, Total, HDL, and LDL cholesterol levels were lowest in patients with more hemolysis (SS<SC<AA, p<.001, Table 1). CONCLUSIONS: We report lower levels of Hp and Hpx in children with SCD (SS<SC<AA). These data support Muller-Eberhard's 1968 brief report on Hp and Hpx levels in hemolytic conditions and demonstrate significant correlations of serum Hp and Hpx with biomarkers of hemolysis, inflammation, and cholesterol. We speculate that serum Hp and Hpx levels in SCD may serve as clinical indicators of hemolysis, inflammation, and disease severity. Disclosures Vercellotti: Imara: Research Funding. Belcher:Cydan/Imara: Research Funding; CSL-Behring: Research Funding.