Sickle cell nephropathy: an update on pathophysiology, diagnosis, and treatment

Systematic Review of Genetic Modifiers Associated with the Development and/or Progression of Nephropathy in Patients with Sickle Cell Disease

Sickle cell nephropathy (SCN) is a common complication of sickle cell disease (SCD) that significantly contributes to morbidity and mortality. In addition to clinical and life-style factors, genetic variants influence this risk. We performed a systematic review, searching five databases. Studies evaluating the effect of genetic modifiers on SCN were eligible. Twenty-eight studies (fair-to-good quality) were included: one genome-wide association study, twenty-six case-control studies, and one article combining both approaches. APOL1 was significantly associated with albuminuria and hyperfiltration in children and with worse glomerular filtration in adults. On the other hand, alpha-thalassemia protected patients against albuminuria and hyperfiltration, while BCL11A variants were protective against albuminuria alone. The HMOX1 long GT-tandem repeat polymorphism led to a lower glomerular filtration rate. No modifiers for the risk of hyposthenuria were identified. A genome-wide association approach identified three new loci for proteinuria (CRYL1, VWF, and ADAMTS7) and nine loci were linked with eGFR (PKD1L2, TOR2A, CUBN, AGGF1, CYP4B1, CD163, LRP1B, linc02288, and FPGT-TNNI3K/TNNI3K). In conclusion, this systematic review supports the role of genetic modifiers in influencing the risk and progression of SCN. Incorporating and expanding this knowledge is crucial to improving the management and clinical outcomes of patients at risk.

Clinicopathologic Study of Sickle Cell-associated Kidney Disease: A Nigerian Experience

BACKGROUND

Improvements in sickle cell disease (SCD) care have resulted in the survival of many patients into adulthood, although this is accompanied by the increased incidence of end-organ damage, including chronic kidney disease (CKD).

OBJECTIVES

This study assessed the prevalence, pattern and predictors of renal dysfunction in SCD patients and investigated the associated renal histopathologic changes.

METHODS

We evaluated 105 patients with SCD, for proteinuria, estimated glomerular filtration rate (eGFR), and tubular dysfunction. Renal biopsy was conducted on 22 patients who qualified. Data were analysed using SPSS package version 23.

RESULTS

Thirty-seven (35.2%) of the 105 patients had CKD, as defined by an eGFR of 60 ml/min/1.73 m2 and/or proteinuria. The fractional excretion of potassium (FEK) was elevated in all patients, whereas the fractional excretion of sodium (FENa) was elevated in 98.1%. Glomerular filtration rate was negatively correlated with irreversible percentage sickle cell count (r = -0.616, P = 0.0001), FEK (r = -0.448, P = 0.0001) and FENa (r = -0.336, P = 0.004). Age, irreversible percentage sickle cell count, haemoglobin levels and FENa were the major predictors of CKD. The histological pattern in the 22 patients who had biopsies was consistent with mesangioproliferative glomerulonephritis 11 (50%), minimal change disease 6 (27.3%), focal segmental glomerulosclerosis 3 (13.6%) and interstitial nephritis 2 (9.1%).

CONCLUSIONS

CKD was prevalent in SCD patients, and it was characterised by tubular dysfunction and mesangioproliferative glomerulonephritis. The main predictors of CKD were increased age, severity of vaso-occlusive crisis, worsening anaemia and tubular dysfunction.

Renal outcomes in pediatric patients with sickle cell disease: a single center experience in Saudi Arabia

Background

Sickle cell nephropathy (SCN) is a significant complication of sickle cell disease (SCD) with an asymptomatic onset in childhood and potential progression to chronic kidney disease (CKD). The clinical findings of SCN include hyposthenuria, hematuria, proteinuria, hyperfiltration, and CKD. Data on renal manifestation among patients with SCD in Saudi Arabia is lacking. Therefore, this study aimed to evaluate renal outcomes in patients with SCD who visited a hematology clinic at the National Guard Hospital, Jeddah.

Methods

We conducted a retrospective chart review of renal complications in patients with SCD who are within 0-14 years of age and on regular follow-ups at the pediatric hematology clinic in King Abdulaziz Medical City-Jeddah, Saudi Arabia.

Results

Among the 140 patients with SCD, 99 met the inclusion criteria. The median age at diagnosis was 18 (1-108) months. Two SCD phenotypes were observed, with 82 (83%) patients having sickle cell anemia (HbSS) and 17 (17%) having HbS/B+ thalassemia. Of the total patients, 92 (93%) were administered hydroxyurea (HU), with a median starting age of 48 (9-168) months. The most common renal complication observed during routine urinalysis was hematuria (38%), followed by proteinuria (11%). After stratifying the sample into four age groups (0-3 years old, 4-7 years old, 8-11 years old, and 12-14 years old), the mean glomerular filtration rate (GFR) values were 96.16, 101.36, 112.69, and 120.11 ml/min/1.73 m2 respectively. Renal imaging revealed abnormal findings in 27 (29%) patients. The most common abnormality observed on US was increased echogenicity (43%).

Conclusion

SCN is a significant complication of SCD. In this study, we assessed the renal outcomes in pediatric patients with SCD. After analyzing the clinical findings of SCN, we concluded that the presence of renal complications in pediatric patients presented a progressive pattern.

Renal Doppler Sonography As A Non-Invasive Technique For Early Detection Of Sickle Nephropathy In Children.. [DOI: 10.21203/rs.3.rs-2902442/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Objective: Early identification of sickle nephropathy via renal doppler sonography among sickle cell disease patients so as to help in early diagnosis and interventions to prevent progression to end-stage renal disease. Methods: 45 SCD children were included along with 45 healthy control children. Renal doppler sonography (PI and RI) was performed to all subjects. Doppler indices (Resistance Index and pulsatility index) were of value to assess reno-vascular changes in SCD. Laboratory investigations were done: Hb electrophoresis, complete blood picture with blood indices, reticulocytic count, liver enzymes (ALT and AST), HCV serology, serum ferritin and lactate dehydrogenese (LDH). Results: The study group consisted of 45 SCD patients, 27 (60%) males with mean age 12 years (± 3 years). By performing renal doppler sonography, it was found that all study group had significantly higher doppler indices (Resistivity index and pulsatility index) compared to the control group. Results of renal doppler sonography revealed, Main renal pulsatility index was positively correlated with main renal resistance index (r=0.454, p=0.002). Conclusion: Roc curve showed that Main Renal Artery Pulsatility index and resistance index index could act as a predictor for sickle cell nephropathy with high sensitivity values. Otherwise, renal doppler indices didn’t show statistically significant correlation with the other studied variables.

The Role of Hyposthenuria in Enuresis Among Paediatric Patients With Sickle Cell Disease

Objectives

Enuresis is common among children with sickle cell disease (SCD). Many risk factors have been postulated, but its relation to hyposthenuria is debatable. This study aimed to determine the prevalence of enuresis in children with SCD in Basrah, Iraq, and to examine its relation with hyposthenuria.

Methods

A cross-sectional epidemiological study was performed on children with SCD who met the inclusion criteria at the Basrah Center for Hereditary Blood Diseases from December 2020 to May 2021. A questionnaire was used to collect relevant data. Blood samples were tested for haemoglobin genotype, certain blood indices and serum haemoglobin. Urine was tested for albumin and creatinine, and the specific gravity was measured using urine dipsticks. The relationships between enuresis and various sociodemographic and clinical variables were assessed. Binary logistic regression analysis was done to examine the independent risk factors of enuresis.

Results

A total of 161 out of 200 eligible children were included in this study (response rate: 80.5%). The majority of participants (60.9%) were males. The mean age of the participants was 10.9 ± 2.9 years. Enuresis was reported in 50 (31.1%) patients. The independent risk factors for enuresis included family history of enuresis (adjusted odds ratio [OR] = 5.94, 95% confidence interval [CI]: 2.54-13.89; P <0.001), hyposthenuria (OR = 3.76, 95% CI: 1.25-11.30; P = 0.018) and sleep disorders (OR = 2.90, 95% CI: 1.19-7.06; P = 0.019.

Conclusion

Enuresis is common among children with SCD in Basrah, Iraq. Hyposthenuria was significantly associated with enuresis. Family history of enuresis and sleep disorders were also found to be significantly related to enuresis.

Plasma levels of E-selectin are associated with retinopathy in sickle cell disease

BACKGROUND

The vascular endothelium is markedly disrupted in sickle cell disease (SCD) and is the converging cascade of the complex pathophysiologic processes linked to sickle cell vasculopathy. Circulating endothelial activation and/or apoptotic markers may reflect this endothelial activation/damage that contributes to the pathophysiology of the SCD vascular complications.

METHODS

Plasmatic levels of circulating endothelial cells (CECs), E-selectin, progenitor's endothelial cells (EPCs), and circulating extracellular vesicles (EVs) were evaluated in 50 SCD patients, 16 with vasculopathy. The association between these markers and the occurrence of disease-related microvascular injuries of the eye (retinopathy), kidney (nephropathy), and skin (chronic active ulcers) was explored.

RESULTS

Among the endothelial activation markers studied, only higher plasma levels of E-selectin were found in SCD patients with vasculopathy (p = .015). Increased E-selectin levels were associated with retinopathy (p < .001) but not with nephropathy or leg ulcers. All patients, at steady state, with or without vasculopathy, did not display a high count of CEC and EPC, markers of endothelial injury and repair. We did not show any significant differences in EVs levels between vasculopathy and not vasculopathy SCD patients.

CONCLUSIONS

Further studies will be required to determine whether the E-selectin could be used as an early biomarker of retinopathy sickle cell development.

Sickle cell anemia: hierarchical cluster analysis and clinical profile in a cohort in Brazil

INTRODUCTION

Sickle cell anemia is a monogenic disorder caused by a mutation in the β-hemoglobin gene, resulting in sickle hemoglobin that can polymerize. Presentation and clinical course have significant inter-individual variability and classifying these patients for severity is a challenge.

METHODS

We applied hierarchical clusters with 10 routine laboratory tests to understand if this grouping could be associated with clinical manifestations. We included 145 adult homozygous patients (SS) at an outpatient clinic in a retrospective study.

RESULTS

We found five clusters by counting those that had been differentiated by unconjugated bilirubin, reticulocytes, LDH, leukocytes, lymphocytes and monocytes. When comparing groups to clinical findings, the clusters were different only for liver abnormality. Cluster 3 had the lower median of reticulocytes, LDH, leukocytes, lymphocytes and monocytes and a higher percentage of patients under treatment. Clusters 4 and 5 had higher frequencies of liver impairment and higher medians of reticulocytes, LDH, leukocytes, lymphocytes and monocytes. Hemolysis and inflammation seemed to influence the grouping.

CONCLUSION

In our study, cluster analysis showed five groups that exhibited different degrees of inflammation and hemolysis. When comparing clinical data, the result was different only for the criteria of liver abnormality.

Emerging drugs for the treatment of sickle cell disease: a review of phase II/III trials

INTRODUCTION

The substitution of glutamic acid by valine on the ß-globin gene produces the hemoglobin S variant responsible for sickle cell disease (SCD), a disorder that affects millions of people worldwide and leads to acute and cumulative organ damage. Even though life expectancy has significantly improved where the best medical care is available, there are still few therapeutic options for SCD and those are limited by their availability, cost, and individual toxicities.

AREAS COVERED

This review summarizes the clinical data on current treatments for SCD and emerging therapies studied in the acute setting as well as potential disease-modifying agents, with an emphasis on the FDA-approved agents.

EXPERT OPINION

Hydroxyurea has been a gold standard for two decades, showing benefits in acute complications and overall survival in sickle cell anemia, although data is lacking for certain genotypes such as hemoglobin SC. As progress is made in our understanding of the pathophysiological networks characterizing SCD, numerous pathways appear to be targetable, with L-glutamine, Crizanlizumab and Voxelotor now approved by the FDA. Pursuing a multi-agent approach could alter the disease course in a more effective fashion and provide an alternative option to curative therapies, but longer clinical studies are needed.

Sickle cell nephropathy: insights into the pediatric population

The life expectancy of individuals with sickle cell disease has increased over the years, majorly due to an overall improvement in diagnosis and medical care. Nevertheless, this improved longevity has resulted in an increased prevalence of chronic complications such as sickle cell nephropathy (SCN), which poses a challenge to the medical care of the patient, shortening the lifespan of patients by 20-30 years. Clinical presentation of SCN is age-dependent, with kidney dysfunction slowly beginning to develop from childhood, progressing to chronic kidney disease and kidney failure during the third and fourth decades of life. This review explores the epidemiology, pathology, pathophysiology, clinical presentation, and management of SCN by focusing on the pediatric population. It also discusses the factors that can modify SCN susceptibility.

Reduced blood pressure in sickle cell disease is associated with decreased angiotensin converting enzyme (ACE) activity and is not modulated by ACE inhibition

Background

Sickle cell disease (SCD) incurs vaso-occlusive episodes and organ damage, including nephropathy. Despite displaying characteristics of vascular dysfunction, SCD patients tend to present relatively lower systemic blood pressure (BP), via an unknown mechanism. We investigated associations between BP and renin-angiotensin-system (RAS) components in SCD and determined whether an inhibitor of angiotensin converting enzyme (ACE; often used to slow SCD glomerulopathy) further modulates BP and RAS components in a murine model of SCD.

Methods

BP was compared in human subjects and mice with/without SCD. Plasma angiotensin II, ACE and renin were measured by immunoassay. BP was reevaluated after treating mice with enalapril (25 mg/kg, 5x/week) for 5 weeks; plasma and organs were stored for angiotensin II and ACE activity measurement, and quantitative real-time PCR.

Results

Diastolic BP and systolic BP were significantly lower in patients and mice with SCD, respectively, compared to controls. Reduced BP was associated with increased plasma renin and markers of kidney damage (mice) in SCD, as well as significantly decreased plasma ACE concentrations and ACE enzyme activity. As expected, enalapril administration lowered BP, plasma angiotensin II and organ ACE activity in control mice. In contrast, enalapril did not further reduce BP or organ ACE activity in SCD mice; however, plasma angiotensin II and renin levels were found to be significantly higher in enalapril-treated SCD mice than those of treated control mice.

Conclusion

Relative hypotension was confirmed in a murine model of SCD, in association with decreased ACE concentrations in both human and murine disease. Given that ACE inhibition has an accepted role in decreasing BP, further studies should investigate mechanisms by which ACE depletion, via both Ang II-dependent and alternative pathways, could contribute to reduce BP in SCD and understand how ACE inhibition confers Ang II-independent benefits on kidney function in SCD.

Sickle cell nephropathy: A review of novel biomarkers and their potential roles in early detection of renal involvement

Whether the underlying mutations are homozygous, heterozygous, or co-inherited with other hemoglobinopathies, sickle cell disease is known to afflict the kidneys, leading to the clinical entity known as sickle cell nephropathy (SCN). Although common, SCN remains diagnostically elusive. Conventional studies performed in the context of renal disorders often fail to detect early stage SCN. This makes the quest for early diagnosis and treatment more challenging, and it increases the burden of chronic kidney disease-related morbidity among patients. Novel diagnostic tools have been employed to overcome this limitation. In this study, we discuss various biomarkers of SCN, including those employed in clinical practice and others recently identified in experimental settings, such as markers of vascular injury, endothelial dysfunction, tubulo-glomerular damage, and oxidative stress. These include kidney injury molecule-1, monocyte chemoattractant protein-1, N-acetyl-B-D-glucosaminidase, ceruloplasmin, orosomucoid, nephrin, and cation channels, among others. Furthermore, we explore the potential of novel biomarkers for refining diagnostic and therapeutic approaches and describe some obstacles that still need to be overcome. We highlight the importance of a collaborative approach to standardize the use of promising new biomarkers. Finally, we outline the limitations of conventional markers of renal damage as extensions of the pathogenic process occurring at the level of the organ and its functional subunits, with a discussion of the expected pattern of clinical and biochemical progression among patients with SCN.

Biomarkers of clinical severity in treated and untreated sickle cell disease: a comparison by genotypes of a single center cohort and African Americans in the NHANES study

Haemolysis and vaso-occlusion underlie multi-organ system complications in sickle cell disease (SCD). We assessed real-world biomarkers in University of Illinois adult SCD patients, categorised as severe (HbSS/Sβ0 -thalassaemia; n = 342) or mild (HbSC/Sβ+ -thalassaemia; n = 100) genotypes and stratified according to treatment. African-American controls from the National Health and Nutrition Examination Survey (NHANES) were matched with each genotype category. Most measures of haemolysis, anaemia, inflammation and function of kidneys, liver and lungs differed markedly in untreated severe genotype patients compared to NHANES controls. These same biomarkers were significantly closer to the NHANES control range in untreated mild versus severe genotype patients, but they were not improved in severe genotype patients receiving treatment with hydroxycarbamide or blood transfusions, except that haemoglobin and HbF were higher with hydroxycarbamide. Systolic blood pressures did not differ among the SCD and NHANES groups, but diastolic pressures were higher in mild genotype patients. Ferritin in severe genotype patients on chronic transfusions was 50-fold higher than NHANES controls. The cross-sectional real-world biomarkers of patients on hydroxycarbamide or transfusions were not markedly improved compared to untreated patients. This may be due partly to poor compliance or more severe disease. Our findings highlight the need for more effective treatments.

Do We Store Packed Red Blood Cells under "Quasi-Diabetic" Conditions?

Red blood cell (RBC) transfusion is one of the most common therapeutic procedures in modern medicine. Although frequently lifesaving, it often has deleterious side effects. RBC quality is one of the critical factors for transfusion efficacy and safety. The role of various factors in the cells’ ability to maintain their functionality during storage is widely discussed in professional literature. Thus, the extra- and intracellular factors inducing an accelerated RBC aging need to be identified and therapeutically modified. Despite the extensively studied in vivo effect of chronic hyperglycemia on RBC hemodynamic and metabolic properties, as well as on their lifespan, only limited attention has been directed at the high sugar concentration in RBCs storage media, a possible cause of damage to red blood cells. This mini-review aims to compare the biophysical and biochemical changes observed in the red blood cells during cold storage and in patients with non-insulin-dependent diabetes mellitus (NIDDM). Given the well-described corresponding RBC alterations in NIDDM and during cold storage, we may regard the stored (especially long-stored) RBCs as “quasi-diabetic”. Keeping in mind that these RBC modifications may be crucial for the initial steps of microvascular pathogenesis, suitable preventive care for the transfused patients should be considered. We hope that our hypothesis will stimulate targeted experimental research to establish a relationship between a high sugar concentration in a storage medium and a deterioration in cells’ functional properties during storage.

COVID-19 and Sickle Cell Disease: a new challenging dilemma in an old disease

Abstract The authors bring reflections about people with sickle cell disease in the pandemic era. They comment on some common clinical situations in these two diseases which may delay or confuse the diagnosis of COVID-19 in patients with sickle cell disease. We consider that people with sickle cell disease are part of the risk group for the complications of COVID-19 and the topic should be addressed in the scientific literature.

Impact of renal function on hydroxyurea exposure in sickle-cell disease patients

AIMS

This prospective study aimed to develop a population pharmacokinetics (PK) model of hydroxyurea (HU) in patients with sickle cell disease. This model can be used to determine the impact of glomerular filtration rate (GFR) on HU kinetics.

METHODS

We included 30 patients. They underwent HU pharmacokinetics analyses of plasma and urine. Six underwent PK analyses in 2 periods with and without angiotensin-converting enzyme inhibitor. HU was assayed with a validated high-performance liquid chromatography-UV method. Noncompartmental PK analysis was conducted and a population PK model built with Monolix. This model was validated externally on another 56 patients. HU PK was simulated as a function of GFR.

RESULTS

The HU PK model was constructed as a 2-compartment model with first-order absorption and elimination. The quality criteria were good, including for external validation. We found that estimated GFR (eGFR) and body weight affected HU PK, with lower eGFR or body weight associated with a higher HU area under the curve. We recommend the monitoring of HU through eGFR and body weight, which together account for 47% of its variability. Urinary HU fractions and renal clearance were higher in the glomerular hyperfiltration group and lower in the moderate chronic kidney disease group, respectively. No differences in nonrenal HU clearance were observed.

CONCLUSION

Estimated GFR has an impact on the kinetics of hydroxyurea, and HU dose should be adapted accordingly. Angiotensin-converting enzyme inhibitor seems to have minor effect on HU PK in adults with sickle cell disease.

Systematic Review of Crizanlizumab: A New Parenteral Option to Reduce Vaso-occlusive Pain Crises in Patients with Sickle Cell Disease

Hydroxyurea, indicated for managing sickle cell anemia (SCA), and L-glutamine, indicated for treating sickle cell disease (SCD), were the only pharmacotherapeutic options in this patient population before the approval of crizanlizumab by the U.S. Food and Drug Administration in November 2019 to reduce vaso-occlusive crisis (VOC) frequency. This article reviews the evidence pertaining to crizanlizumab in SCD by searching records in Medline, Embase, and International Pharmaceutical Abstracts. Crizanlizumab, a P-selectin inhibitor, mitigates the microvascular vaso-occlusion in SCD. In the multicenter randomized double-blind SUSTAIN trial, a higher dose of crizanlizumab decreased the incidence of VOCs by 45% and prolonged the median time to the first and second VOC. A post hoc subgroup analysis demonstrated that the proportion of patients who had no VOC incidence during the study period was greater in the crizanlizumab group, and this benefit was consistent regardless of concomitant hydroxyurea use, prior categorized history of VOC frequency, or SCD genotype. Crizanlizumab had a safety profile comparable with placebo. Multiple ongoing clinical trials are trying to establish its roles in pediatric patients with SCD and its effects on alleviating other SCD-related complications. As the first parenteral option for SCD, providers need to formulate administration logistics to improve patients' access to crizanlizumab. Current available data suggest crizanlizumab is a promising agent to reduce VOC in patients with SCD.

Atypical presentation of acute post-infectious glomerulonephritis in patients with sickle cell disease: report of two cases

BACKGROUND

Sickle cell disease (SCD) is a highly prevalent genetic disease worldwide. In the natural evolution of SCD, glomerular lesions can develop, presenting histopathological patterns of segmental or focal membranoproliferative glomerulosclerosis, with or without thrombotic microangiopathy. We report two cases of acute post-infectious glomerulonephritis (APIGN), with atypical presentations, in patients with SCD.

CASE PRESENTATION

Case 1: An 18-year-old female with SCD presented with a 21-day history of progressive oedema, accompanied by dyspnoea, productive cough, fever, and chest pain. Blood tests showed the following: haemoglobin 6.1 g/dl; leucocytes 18,820 cells/mm³; and creatinine 0.49 mg/dl. A urine sample evidenced leucocyturia and haematuria. The 24-h proteinuria was 8.99 g, serum albumin level was 1.2 g/dl, low serum C3 levels and high levels of anti-streptolysin O. Renal biopsy was consistent with APIGN. The patient was treated with diuretic and anti-proteinuric agents, subsequently evolving to reversal of the renal alterations. Case 2: A 12-year-old male with SCD presented with a 20-day history of a non-productive cough and progressive oedema, together with hypertension. The serum creatinine concentration was 0.48 mg/dl. A urine sample evidenced leukocyturia and haematuria. The 24-h proteinuria was 12.5 g, and the serum albumin level was 2.6 g/dl. The levels of C3 and C4 were normal. Renal biopsy revealed APIGN. The patient was treated with diuretic and anti-proteinuric agents, subsequently evolving reversal of the renal alterations.

CONCLUSIONS

The presentation of the two cases reported here are not typical of SCD-related kidney injury. Analysis of the renal biopsy specimens elucidated the diagnosis, affecting the prognosis, because that of APIGN is highly favourable, unlike that of nephrotic syndrome associated with SCD glomerulopathy.

Non-invasive urinary biomarkers of renal function in sickle cell disease: an overview

Sickle cell disease (SCD) is a hereditary condition characterized by homozygosis of the hemoglobin S (HbS) gene. Marked morbimortality is observed due to chronic hemolysis, endothelial injury, and episodes of vaso-occlusion, which leads to multi-organ damage. Renal impairment is common and may have different presentations, such as deficiency in urinary acidification or concentration, glomerulopathies, proteinuria, and hematuria, frequently resulting in end-stage renal disease (ESRD). Novel biomarkers of renal function, such as kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) and monocyte chemoattractant protein 1 (MCP-1) are being studied in order to enable early diagnosis of kidney damage in SCD.

Technetium-99m-dimercaptosuccinic acid renal scintigraphy and single photon emission computed tomography/computed tomography in patients with sickle cell disease

PURPOSE

Sickle cell disease (SCD) is a common hematologic hereditary disorder characterized by vaso-occlusive episodes affecting multiple organs, and substantially alters renal structure and function. We aimed to evaluate the utility of renal scintigraphy and single photon emission computed tomography/computed tomography (SPECT/CT) with technetium-99m-dimercaptosuccinic acid (Tc-DMSA) in adult patients with SCD and no clinical evidence of renal insufficiency.

MATERIALS AND METHODS

Twenty-six patients (16 female) aged 23-58 years with SCD and no clinical evidence of renal insufficiency were prospectively studied. Planar and SPECT/CT images were, respectively, obtained after 3 and 4 hours of the injection of 110-180 MBq of Tc-DMSA. The relative radiopharmaceutical uptake and renal length were, respectively, determined using SPECT and CT images. Planar and SPECT/CT images were visually analyzed to identify focal areas of Tc-DMSA reduced uptake and anatomical deformities of the kidneys.

RESULTS

Focal areas of reduced Tc-DMSA uptake with an image aspect of renal scars or inflammation were present in 21/26 patients (81%). In 11/21 (52%) of these patients, the cortical lesions were clearly identified only on SPECT images. Prominent renal columns were observed in 17/26 (65%) patients. The left kidney tended to be more affected than the right kidney. Most patients had enlarged kidneys.

CONCLUSION

Tc-DMSA scintigraphy and SPECT/CT identify renal lesions possible related to renal infarcts or infections in most adult patients with SCD and no clinical evidence of renal insufficiency. Prominent renal columns and increased renal size tend to occur in most of these patients.

Sickle cell disease nephropathy: an update on risk factors and potential biomarkers in pediatric patients

One of the major chronic complications of sickle cell disease (SCD) is sickle cell nephropathy. The aim of this review is to discuss the pathophysiology, natural history, clinical manifestations, risk factors, biomarkers and therapeutic approaches for sickle cell nephropathy, focusing on studies with pediatric patients. The earliest manifestation of renal disease is an increase in the glomerular filtration rate. A finding that may also be observed in early childhood is microalbuminuria. Nephrin, KIM-1, VGFs, chemokines and renin-angiotensin system molecules have emerged as potential early markers of renal dysfunction in SCD. In regards to a therapeutic approach, renin-angiotensin system inhibitors and angiotensin receptor blockers seem to be effective for the control of albuminuria in adults with SCD, although new studies in children are needed. The precise moment to begin renoprotection in SCD patients who should be treated remains to be determined.

VEGF Promoter Region 18-bp Insertion-Deletion Polymorphism in Sickle Cell Disease Patients with Microalbuminuria: A Pilot Study

Purpose

Vascular endothelial growth factor (VEGF) is a potent inducer of micro vascular permeability thus leading to nephropathy. Insertion/deletion (I/D) polymorphism of 18 bp at - 2549 position in VEGF gene causes increased transcription leading to increased production of VEGF. Thus, we aimed to associate I/D polymorphism of the 18 bp fragment at - 2549 position of the promoter region of VEGF gene with sickle cell nephropathy (SCN).

Methods

This observational analytical case control study included 30 subjects each of SCN, sickle cell disease (SCD) without nephropathy and the control group. The subjects were assessed for various hematological and biochemical parameters. Further, 18 bp I/D polymorphism of VEGF gene in all three study groups was assessed by polymerase chain reaction followed by electrophoresis and compared.

Result

Though increased frequency of both DD genotype and D allele was found in SCN compared to SCD and control, only frequency of D allele was found to be significantly higher (p = 0.04). D allele posed marginal risk of microalbuminuria in SCD subjects compared to controls (OR = 2.11) as well as to SCD without MA subjects (OR = 1.84).

Conclusion

D allele in I/D polymorphism in the promoter region of VEGF gene may be associated with marginal increase in risk of susceptibility to sickle cell nephropathy.

cGMP modulation therapeutics for sickle cell disease

IMPACT STATEMENT

Sickle cell disease (SCD) is one of the most common inherited diseases and is associated with a reduced life expectancy and acute and chronic complications, including frequent painful vaso-occlusive episodes that often require hospitalization. At present, treatment of SCD is limited to hematopoietic stem cell transplant, transfusion, and limited options for pharmacotherapy, based principally on hydroxyurea therapy. This review highlights the importance of intracellular cGMP-dependent signaling pathways in SCD pathophysiology; modulation of these pathways with soluble guanylate cyclase (sGC) stimulators or phosphodiesterase (PDE) inhibitors could potentially provide vasorelaxation and anti-inflammatory effects, as well as elevate levels of anti-sickling fetal hemoglobin.