scholarly journals Rapid and inefficient kinetics of sickle hemoglobin fiber growth

2019 ◽  
Vol 5 (3) ◽  
pp. eaau1086 ◽  
Author(s):  
Brian T. Castle ◽  
David J. Odde ◽  
David K. Wood

In sickle cell disease, the aberrant assembly of hemoglobin fibers induces changes in red blood cell morphology and stiffness, which leads to downstream symptoms of the disease. Therefore, understanding of this assembly process will be important for the treatment of sickle cell disease. By performing the highest spatiotemporal resolution measurements (55 nm at 1 Hz) of single sickle hemoglobin fiber assembly to date and combining them with a model that accounts for the multistranded structure of the fibers, we show that the rates of sickle hemoglobin addition and loss have been underestimated in the literature by at least an order of magnitude. These results reveal that the sickle hemoglobin self-assembly process is very rapid and inefficient (4% efficient versus 96% efficient based on previous analyses), where net growth is the small difference between over a million addition-loss events occurring every second.

Genes ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 144
Author(s):  
Olivia Edwards ◽  
Alicia Burris ◽  
Josh Lua ◽  
Diana J. Wilkie ◽  
Miriam O. Ezenwa ◽  
...  

This review outlines the current clinical research investigating how the haptoglobin (Hp) genetic polymorphism and stroke occurrence are implicated in sickle cell disease (SCD) pathophysiology. Hp is a blood serum glycoprotein responsible for binding and removing toxic free hemoglobin from the vasculature. The role of Hp in patients with SCD is critical in combating blood toxicity, inflammation, oxidative stress, and even stroke. Ischemic stroke occurs when a blocked vessel decreases oxygen delivery in the blood to cerebral tissue and is commonly associated with SCD. Due to the malformed red blood cells of sickle hemoglobin S, blockage of blood flow is much more prevalent in patients with SCD. This review is the first to evaluate the role of the Hp polymorphism in the incidence of stroke in patients with SCD. Overall, the data compiled in this review suggest that further studies should be conducted to reveal and evaluate potential clinical advancements for gene therapy and Hp infusions.


2019 ◽  
Vol 3 (8) ◽  
pp. 1347-1355 ◽  
Author(s):  
Morayo G. Adebiyi ◽  
Jeanne M. Manalo ◽  
Yang Xia

Abstract Sickle cell disease (SCD) is an autosomal-recessive hemolytic disorder with high morbidity and mortality. The pathophysiology of SCD is characterized by the polymerization of deoxygenated intracellular sickle hemoglobin, which causes the sickling of erythrocytes. The recent development of metabolomics, the newest member of the “omics” family, has provided a powerful new research strategy to accurately measure functional phenotypes that are the net result of genomic, transcriptomic, and proteomic changes. Metabolomics changes respond faster to external stimuli than any other “ome” and are especially appropriate for surveilling the metabolic profile of erythrocytes. In this review, we summarize recent pioneering research that exploited cutting-edge metabolomics and state-of-the-art isotopically labeled nutrient flux analysis to monitor and trace intracellular metabolism in SCD mice and humans. Genetic, structural, biochemical, and molecular studies in mice and humans demonstrate unrecognized intracellular signaling pathways, including purinergic and sphingolipid signaling networks that promote hypoxic metabolic reprogramming by channeling glucose metabolism to glycolysis via the pentose phosphate pathway. In turn, this hypoxic metabolic reprogramming induces 2,3-bisphosphoglycerate production, deoxygenation of sickle hemoglobin, polymerization, and sickling. Additionally, we review the detrimental role of an impaired Lands’ cycle, which contributes to sickling, inflammation, and disease progression. Thus, metabolomic profiling allows us to identify the pathological role of adenosine signaling and S1P-mediated erythrocyte hypoxic metabolic reprogramming and hypoxia-induced impaired Lands' cycle in SCD. These findings further reveal that the inhibition of adenosine and S1P signaling cascade and the restoration of an imbalanced Lands' cycle have potent preclinical efficacy in counteracting sickling, inflammation, and disease progression.


Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4235-4235
Author(s):  
Genevieve Arty ◽  
Rotz Seth ◽  
Prasad Bodas ◽  
Lucia De Zen ◽  
Francesco Angelo Zanolli ◽  
...  

Abstract Abstract 4235 Background In the United States, four decades of advances in the treatment of sickle cell disease have reduced mortality rates of affected children from greater than 50% to well below 5%. The greatest impacts have come from inexpensive, non-burdensome interventions. The effectiveness of these interventions relies on universal newborn screening, case-finding, and targeted intervention. We sought to determine the prevalence of sickle cell disease among Haitian newborns and demonstrate feasibility of a hemoglobinopathy screening effort at a large scale. Haiti, the poorest country in the Western Hemisphere, lacks newborn screening. One study examined incidence of hemoglobinopathy traits (HbS and HbC) among infants of recent Haitian immigrants in Maimi, FL, USA, and reported an incidence of 8% and 4.7%. The study was limited by small sample size, and a population that might differ from native Haitians. Another study examining the prevalence of sickle hemoglobin among healthy adult volunteers in Northern Haiti, reported at 15.5%. Testing methods did not distinguish trait from homozygous disease, though volunteers were clinically well. In a previously published pilot study, our group sought to address these limitations through direct screening of newborns. We screened 259 newborns. We demonstrated prevalence of S trait, SS disease, and SC disease of 10%, 1.5%, and 1.5% respectively. In this report we present an update and demonstrate the scalability and feasibility of our approach in a much larger population. Methods 2459 consecutive newborns at Saint Damien Pediatric Hospital in Port-Au-Prince, Haiti in 2010 were screened for detection of hemoglobin types F,A,S,C,D, and E to establish prevalence of Sickle Hemoglobin. Heel-prick specimens were obtained and placed on filter paper (S&S 903, Schleicher & Schuell, New Hampshire, USA) and sent to Pordenone Hospital, Italy. Screening was performed using the Variant HPLC system (Bio-Rad Laboratories, California, USA), then Variant NBS HPLC system (Bio-Rad Laboratories, California, USA). Our project has evolved from screening only, to active case finding and provision of comprehensive disease management. The program is driven by local physician leaders and supported by a multinational team of academic and clinical staff. Results Among 2459 screened neonates 2258 specimens were able to be tested. 201 were unable to be tested due to technical issues with samples. Of the 2258 samples tested, 247 had HbS, fifty-seven had HbC, ten had HbSS, and three had HbSC. This yields a prevalence of 10.9%, 2.5%, 0.44% and 0.13% respectively. This corresponds to the prevalence of HbSC or HbSS of one in one hundred seventy three newborns. Conclusions Sickle cell disease is highly prevalent in Haiti, warranting universal screening and treatment efforts. We have demonstrated feasibility of newborn screening in Haiti. We recognize that challenges will exist in expanding this project to remote settings. Further, given that 78% of children in Haiti are born outside of hospitals, challenges to screening these patients remain. Nonetheless, this project provides valuable data at a scale suitable to inform clinical decision-making as well as health policy development. Disclosures: No relevant conflicts of interest to declare.


2021 ◽  
Author(s):  
Eric O. Olori ◽  
Olujide Oludayo Olubiyi ◽  
Chinedum Peace Babalola

In sickle cell disease, a hereditary hemoglobinopathy, clinically observed disease presentations are the endpoint of a point mutation involving the substitution of glutamic acid with valine at the position 6 of the beta globin chain. With about 4.4 million people globally being affected, and another 43 million people bearing the sickle cell trait, several research efforts have been made to discover new and affordable treatment and possibly cure for the disease. Africa is endowed with a large flora population and traditional healers and citizens have over time depended on the use of herbs in folkloric medicine for different ailments including sickle cell disease (SCD). Such native knowledge has often formed the basis for different research exploration into the anti-sickling activities of selected African plants. These plants that have been so far investigated for their anti-sickling properties represent about 0.05 % of the 45,000 plant species enriching the flora landscape in Sub-Saharan Africa. Some of these have yielded potent anti-sickling profiles. In the current work we seek to achieve a more extensive search of the African plant diversity with anti-sickling properties: for this we have adopted a hybrid computational-cum-experimental protocol that employed computer-aided drug design (CADD) means for identifying plants with at least one constituent capable of interacting with the sickle hemoglobin, followed by extractive procedures and anti-sickling experiments for validating the predictions. Over two thousand (or 2,000) African natural products, representing over 200 plant species, were first virtually screened against the crystal structure of the dimerized human sickle hemoglobin. The natural products with the best computed sickle hemoglobin interaction energetics were found to belong to five plant species including Catharanthus roseus, Rauvolfia vomitoria, Hoslundia opposita, Lantana camara and Euphorbia hirta. The leaves of these plants were each collected subsequently and subjected to standard processing and extraction procedures. Using both HbSS polymerization inhibition and sickling reversal tests significant reductions in polymerization of erythrocyte hemolysate of the HbSS genotype were observed with the methanolic extracts of the plants, as well as sickling reversal levels of up to 68.50 % (H. opposita) was observed.


Blood ◽  
1976 ◽  
Vol 47 (1) ◽  
pp. 121-131 ◽  
Author(s):  
MR Clark ◽  
SB Shohet

Abstract A hybrid erythrocyte model for membrane studies in sickle cell disease has been developed. The model consists of normal red cell membranes containing hemoglobin S and sickle cell membranes containing hemoglobin A. In hybrids, complete hemoglobin exchange has been achieved together with restoration of low membrane permeability to potassium. Normal membranes containing HbS sickle upon deoxygenation and assume the characteristic appearance of irreversibly sickled cells (ISC) after prolonged anoxia. It is suggested that the hybrid model will be useful in defining further the process of ISC formation and in studying the influence of sickle hemoglobin upon the function of the surrounding membrane.


MedChemComm ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 1900-1906 ◽  
Author(s):  
A. M. Omar ◽  
T. David ◽  
P. P. Pagare ◽  
M. S. Ghatge ◽  
Q. Chen ◽  
...  

The intracellular polymerization and the concomitant sickling processes, central to the pathology of sickle cell disease, can be mitigated by increasing the oxygen affinity of sickle hemoglobin (HbS).


Author(s):  
Michael R. Lewis ◽  
Robert Josephs

Sickle cell disease is caused by the self assembly of deoxy-sickle hemoglobin (HbS) into fibers which rigidify and distort red cells. Fiber assembly is auto-catalytic in that the surface of existing fibers acts as a nucleating template for the assembly of new fibers (heterogeneous nucleation). Thus fibers are found typically as bundles of aligned particles. Understanding fiber-fiber interaction is crucial to understanding the pathology of fiber formation. Moreover, disrupting fiber-fiber interactions would likely ameliorate the severity of the disease. We have obtained images of both laterally associated and isolated fibers by cryo-electron microscopy (Figure 1). Optical diffraction indicates that laterally associated fibers tend to have much better long range order than isolated fibers. This observation suggests that deoxy-HbS fibers are more disordered when they are not mechanically coupled by inter-fiber contacts. In this study we assess the effects of fiber-fiber interactions on torsional disorder of deoxy-HbS fibers.


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