scholarly journals Pathophysiology of Sickle Cell Disease

Author(s):  
Prithu Sundd ◽  
Mark T. Gladwin ◽  
Enrico M. Novelli

Since the discovery of sickle cell disease (SCD) in 1910, enormous strides have been made in the elucidation of the pathogenesis of its protean complications, which has inspired recent advances in targeted molecular therapies. In SCD, a single amino acid substitution in the β-globin chain leads to polymerization of mutant hemoglobin S, impairing erythrocyte rheology and survival. Clinically, erythrocyte abnormalities in SCD manifest in hemolytic anemia and cycles of microvascular vaso-occlusion leading to end-organ ischemia-reperfusion injury and infarction. Vaso-occlusive events and intravascular hemolysis promote inflammation and redox instability that lead to progressive small- and large-vessel vasculopathy. Based on current evidence, the pathobiology of SCD is considered to be a vicious cycle of four major processes, all the subject of active study and novel therapeutic targeting: ( a) hemoglobin S polymerization, ( b) impaired biorheology and increased adhesion-mediated vaso-occlusion, ( c) hemolysis-mediated endothelial dysfunction, and ( d) concerted activation of sterile inflammation (Toll-like receptor 4– and inflammasome-dependent innate immune pathways). These molecular, cellular, and biophysical processes synergize to promote acute and chronic pain and end-organ injury and failure in SCD. This review provides an exhaustive overview of the current understanding of the molecular pathophysiology of SCD, how this pathophysiology contributes to complications of the central nervous and cardiopulmonary systems, and how this knowledge is being harnessed to develop current and potential therapies.

Hematology ◽  
2018 ◽  
Vol 2018 (1) ◽  
pp. 493-506 ◽  
Author(s):  
Scott Moerdler ◽  
Deepa Manwani

Abstract Although the seminal event in sickle cell disease is the polymerization of abnormal hemoglobin, the downstream pathophysiology of vasoocclusion results from heterotypic interactions between the altered, adhesive sickle cell red blood cells, neutrophils, endothelium, and platelets. Ischemia reperfusion injury, hemolysis, and oxidant damage all contribute to heightened inflammation and activation of the hemostatic system. These various pathways are the focus of emerging treatments with potential to ameliorate disease manifestations. This review summarizes the considerable progress in development of these agents despite challenges in selection of study end points and complex pathophysiology.


Hematology ◽  
2008 ◽  
Vol 2008 (1) ◽  
pp. 177-185 ◽  
Author(s):  
Claudia R. Morris

AbstractMany mechanisms contribute to the complex pathophysiology of sickle cell disease (SCD), with dysfunction of the vascular endothelium as a unifying theme. Specifically, hemolysis-associated low arginine and nitric oxide (NO) bioavailability, amplified by NO synthase uncoupling, elevated arginase activity, superoxide production, oxidative stress, accumulation of arginine analogs such as asymmetric dimethylarginine, ischemia-reperfusion injury, inflammation, apolipoprotein A-1 depletion, and a hypercoagulable state are significant mechanisms contributing to endothelial dysfunction. Genetic polymorphisms also influence disease severity. Clearly the variable spectrum of disease is the consequence of multiple events and genetic susceptibility that go beyond the occurrence of a single amino acid substitution in the beta globin chain of hemoglobin. Recent studies begin to demonstrate overlap among these seemingly unrelated processes. Impaired NO bioavailability represents the central feature of endothelial dysfunction, and is a common denominator in the pathogenesis of vasculopathy in SCD. The consequences of decreased NO bioavailability include endothelial cell activation, upregulation of the potent vasoconstrictor endothelin-1, vasoconstriction, platelet activation, increased tissue factor, and activation of coagulation, all of which ultimately translate into the clinical manifestations of SCD. Evidence supporting vasculopathy subphenotypes in SCD, including pulmonary hypertension, priapism, cutaneous leg ulceration, and stroke, will be reviewed and relevance to other hemolytic disorders including the thalassemia syndromes will be considered.


Blood ◽  
2017 ◽  
Vol 130 (22) ◽  
pp. 2377-2385 ◽  
Author(s):  
Huy Tran ◽  
Mihir Gupta ◽  
Kalpna Gupta

Abstract Patients with sickle cell disease (SCD) suffer from intense pain that can start during infancy and increase in severity throughout life, leading to hospitalization and poor quality of life. A unique feature of SCD is vaso-occlusive crises (VOCs) characterized by episodic, recurrent, and unpredictable episodes of acute pain. Microvascular obstruction during a VOC leads to impaired oxygen supply to the periphery and ischemia reperfusion injury, inflammation, oxidative stress, and endothelial dysfunction, all of which may perpetuate a noxious microenvironment leading to pain. In addition to episodic acute pain, patients with SCD also report chronic pain. Current treatment of moderate to severe pain in SCD is mostly reliant upon opioids; however, long-term use of opioids is associated with multiple side effects. This review presents up-to-date developments in our understanding of the pathobiology of pain in SCD. To help focus future research efforts, major gaps in knowledge are identified regarding how sickle pathobiology evokes pain, pathways specific to chronic and acute sickle pain, perception-based targets of “top-down” mechanisms originating from the brain and neuromodulation, and how pain affects the sickle microenvironment and pathophysiology. This review also describes mechanism-based targets that may help develop novel therapeutic and/or preventive strategies to ameliorate pain in SCD.


Hematology ◽  
2017 ◽  
Vol 2017 (1) ◽  
pp. 546-555 ◽  
Author(s):  
Huy Tran ◽  
Mihir Gupta ◽  
Kalpna Gupta

Abstract Patients with sickle cell disease (SCD) suffer from intense pain that can start during infancy and increase in severity throughout life, leading to hospitalization and poor quality of life. A unique feature of SCD is vaso-occlusive crises (VOCs) characterized by episodic, recurrent, and unpredictable episodes of acute pain. Microvascular obstruction during a VOC leads to impaired oxygen supply to the periphery and ischemia reperfusion injury, inflammation, oxidative stress, and endothelial dysfunction, all of which may perpetuate a noxious microenvironment leading to pain. In addition to episodic acute pain, patients with SCD also report chronic pain. Current treatment of moderate to severe pain in SCD is mostly reliant upon opioids; however, long-term use of opioids is associated with multiple side effects. This review presents up-to-date developments in our understanding of the pathobiology of pain in SCD. To help focus future research efforts, major gaps in knowledge are identified regarding how sickle pathobiology evokes pain, pathways specific to chronic and acute sickle pain, perception-based targets of “top-down” mechanisms originating from the brain and neuromodulation, and how pain affects the sickle microenvironment and pathophysiology. This review also describes mechanism-based targets that may help develop novel therapeutic and/or preventive strategies to ameliorate pain in SCD.


PEDIATRICS ◽  
1974 ◽  
Vol 54 (4) ◽  
pp. 438-441
Author(s):  
Gerald Erenberg ◽  
Steven S. Rinsler ◽  
Bernard G. Fish

Four cases of lead neuropathy in children with hemoglobin S-S or S-C disease are reported. Neuropathy is a rare manifestation of lead poisoning in children, and only ten other cases have been well documented in the pediatric literature. The last previous case report of lead neuropathy was also in a child with hemoglobin S-S disease. The neuropathy seen in the children with sickle cell disease was clinically similar to that seen in the previously reported cases in nonsicklers, but differed in both groups from that usually seen in adult cases. It is, therefore, postulated that children with sickle cell disease have an increased risk of developing neuropathy with exposure to lead. The exact mechanism for this association remains unknown, but in children with sickle cell disease presenting with symptoms or signs of peripheral weakness, the possibility of lead poisoning must be considered.


2012 ◽  
Vol 2012 ◽  
pp. 1-3 ◽  
Author(s):  
Donovan Calder ◽  
Maryse Etienne-Julan ◽  
Marc Romana ◽  
Naomi Watkins ◽  
Jennifer M. Knight-Madden

A patient who presented with sickle retinopathy and hemoglobin electrophoresis results compatible with sickle cell trait was found, on further investigation, to be a compound heterozygote with hemoglobin S and hemoglobin New York disease. This recently reported form of sickle cell disease was not previously known to cause retinopathy and surprisingly was observed in a non-Asian individual. The ophthalmological findings, the laboratory diagnosis, and possible pathophysiology of this disorder are discussed. Persons diagnosed with sickle cell trait who present with symptoms of sickle cell disease may benefit from specific screening for this variant.


Author(s):  
Mohamed Almuqamam ◽  
◽  
Swetha Madhavarapu ◽  
Nataly Apollonsky ◽  
◽  
...  

Sickle Cell Disease (SCD) is an inherited hemoglobinopathy, which results in production of abnormal hemoglobin S. HbSC disease is a variant of SCD, which shares a similar clinical complication profile to HbSS disease, but often thought to be a milder condition. In patients with SCD, Hb S in deoxygenated state undergoes polymerization, leading to hemolysis, vaso-occlusive events, and eventually end-organ damage. Among other complications in patients with SCD is increased risk of complications caused by parvovirus B19. We present a case of a 14-year-old female with HbSC disease who presented to the emergency room with complaint of abdominal pain and found to have splenic sequestration. Splenic sequestration progressed rapidly, Hemoglobin (hb) dropped to 4.6 g/dl and acute chest syndrome (ACS) developed. She was treated following the ACS protocol, received 4 units of Packed Red Blood Cells (PRBC) and subsequently underwent a single volume PRBC exchange transfusion. Considering her unusual presentation, with severe ARDS from alveolar hemorrhage requiring mechanical ventilation and multi-organ injury, several autoimmune and infectious conditions with a cytokine storm component including COVID-19 disease, were considered. Results of viral testing revealed parvovirus B19 IgM antibodies signifying an acute infection. She fully recovered with supportive care and was discharged home. Multisystem involvement simulating connective tissue disorders or malignancies with acute parvovirus B19 infection has been reported and is considered extremely rare. To our knowledge, there were no reports of pediatric patients with SC disease presenting with splenic sequestration and ACS in the setting of parvovirus B19 multisystem disease. Keywords: sickle cell disease; acute respiratory distress syndrome; acute chest syndrome; parvovirus B19.


PEDIATRICS ◽  
1988 ◽  
Vol 81 (6) ◽  
pp. 749-755
Author(s):  
Elliott Vichinsky ◽  
Deborah Hurst ◽  
Ann Earles ◽  
Klara Kleman ◽  
Bertram Lubin

Newborn screening for sickle cell disease has been recommended as a method of decreasing patient mortality. However, its effectiveness in accomplishing this has not been reliably measured. To help determine the effectiveness, 10 years of experience in newborn screening have been summarized. The effects of early patient enrollment in a comprehensive treatment program on long-term morbidity and mortality are reported. From 1975 to 1985, 84,663 newborns were screened regardless of race or ethnic background. Bart's hemoglobin was present in 5%, hemoglobin AS in 2.6%, and hemoglobin AC in 0.75%. Excluding Bart's, approximately 3.6% of all newborns were carriers for hemoglobinopathy. Sickle cell disease occurred in 1:951 births (58 hemoglobin SS, 25 hemoglobin FSC, three hemoglobin S-β+-thalassemia, and three hemoglobin S-β°-thalassemia). In addition, one in every 4,233 newborns had a clinically significant thalassemia syndrome (eight hemoglobin FE, ten hemoglobin F only, two hemoglobin H). Compared with other newborn screening programs in California, (congenital hypothyroidism, 1:3,849; phenylketonuria 1:22,474, galactosemia 1:74,103), hemoglobinopathies are the most prevalent congenital disease. Eighty-one newborns with sickle cell disease were followed for 7.2 years. Patients experienced 513 hospitalizations, including 13 episodes of sepsis with or without meningitis and ten acute sequestration crises. The overall mortality rate for patients with sickle cell anemia diagnosed in the newborn period was 1.8%. In comparison, the clinical course of 64 patients with sickle cell anemia diagnosed after 3 months of age and followed for an average of 9.4 years was analyzed. Five of these patients died. In two of these, sickle cell anemia was diagnosed at the time of the death. Overall mortality rate in this group was 8%. In summary, the data indicate that newborn screening, when coupled with extensive follow-up and education, will significantly decrease patient mortality.


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