Implication of HMOX1 and CCR5 genotypes on clinical phenotype of Egyptian patients with sickle cell anemia

Prevalence and Impact of HMOX1 Polymorphism (rs2071746: A > T) in Indian Sickle Cell Disease Patients

Introduction  Fetal hemoglobin (HbF) levels play significant role in lowering down the morbidity and mortality in sickle cell disease (SCD) patients. Coinheritance of heme oxygenase-1 (HMOX1) rs2071746:A > T polymorphism may contribute to variable HbF levels in Indian SCD patients. Objective  This study was aimed to evaluate the role of HMOX1 polymorphism and its impact on HbF level in Indian SCD patients. Materials and Methods  One-hundred twenty confirmed cases of SCD and 50 healthy controls were recruited. Their mean age was 11.5 ± 8.6 years (range: 3-23 years). Quantification of Hb, HbA2, HbF, and HbS was done by capillary zone electrophoresis. Allele-specific polymerase chain reaction was used to genotype HMOX1 (rs2071746:A > T) gene polymorphism. Results  Out of the 120 cases of SCD, 65 were hemoglobin sickle-shaped (HbSS) and 55 were sickle-beta thalassemia (Sβ). Out of 65 HbSS patients, 29 (44.6%) were heterozygous (AT), 20 (30.76%) were homozygous (TT), and 16 (24.61%) were found wild-type (AA) genotype. Out of 55 Sβ, 22 (40%) were heterozygous, 18 (32%) were homozygous and 15 (28%) were wild-type. Patients carrying HMOX1 (rs2071746:A > T), AT, and TT genotypes had less anemia, painful crisis, splenomegaly, hepatomegaly, jaundice, and blood transfusion. HbF level was found higher in TT genotype (in HbSS the HbF levels was 25.1 ± 4.4; in sickle-beta thalassemia the HbF levels was 36.1 ± 4.7) than wild-type(AA) and was statistically significant ( p -value <0.001). Conclusion  The TT genotype of the rs2071746:A > T polymorphism was associated with increased levels of Hb F ( p  < 0.001). It can serve as a HbF modifier in Indian sickle cell diseases patients.

Genetic Variation and Sickle Cell Disease Severity: A Systematic Review and Meta-Analysis

Importance

Sickle cell disease (SCD) is a monogenic disorder, yet clinical outcomes are influenced by additional genetic factors. Despite decades of research, the genetics of SCD remain poorly understood.

Objective

To assess all reported genetic modifiers of SCD, evaluate the design of associated studies, and provide guidelines for future analyses according to modern genetic study recommendations.

Data Sources

PubMed, Web of Science, and Scopus were searched through May 16, 2023, identifying 5290 publications.

Study Selection

At least 2 reviewers identified 571 original, peer-reviewed English-language publications reporting genetic modifiers of human SCD phenotypes, wherein the outcome was not treatment response, and the comparison was not between SCD subtypes or including healthy controls.

Data Extraction and Synthesis

Data relevant to all genetic modifiers of SCD were extracted, evaluated, and presented following STREGA and PRISMA guidelines. Weighted z score meta-analyses and pathway analyses were conducted.

Main Outcomes and Measures

Outcomes were aggregated into 25 categories, grouped as acute complications, chronic conditions, hematologic parameters or biomarkers, and general or mixed measures of SCD severity.

Results

The 571 included studies reported on 29 670 unique individuals (50% ≤ 18 years of age) from 43 countries. Of the 17 757 extracted results (4890 significant) in 1552 genes, 3675 results met the study criteria for meta-analysis: reported phenotype and genotype, association size and direction, variability measure, sample size, and statistical test. Only 173 results for 62 associations could be cross-study combined. The remaining associations could not be aggregated because they were only reported once or methods (eg, study design, reporting practice) and genotype or phenotype definitions were insufficiently harmonized. Gene variants regulating fetal hemoglobin and α-thalassemia (important markers for SCD severity) were frequently identified: 19 single-nucleotide variants in BCL11A, HBS1L-MYB, and HBG2 were significantly associated with fetal hemoglobin (absolute value of Z = 4.00 to 20.66; P = 8.63 × 10-95 to 6.19 × 10-5), and α-thalassemia deletions were significantly associated with increased hemoglobin level and reduced risk of albuminuria, abnormal transcranial Doppler velocity, and stroke (absolute value of Z = 3.43 to 5.16; P = 2.42 × 10-7 to 6.00 × 10-4). However, other associations remain unconfirmed. Pathway analyses of significant genes highlighted the importance of cellular adhesion, inflammation, oxidative and toxic stress, and blood vessel regulation in SCD (23 of the top 25 Gene Ontology pathways involve these processes) and suggested future research areas.

Conclusions and Relevance

The findings of this comprehensive systematic review and meta-analysis of all published genetic modifiers of SCD indicated that implementation of standardized phenotypes, statistical methods, and reporting practices should accelerate discovery and validation of genetic modifiers and development of clinically actionable genetic profiles.

The BACH1 inhibitor ASP8731 inhibits inflammation and vaso-occlusion and induces fetal hemoglobin in sickle cell disease

In sickle cell disease (SCD), heme released during intravascular hemolysis promotes oxidative stress, inflammation, and vaso-occlusion. Conversely, free heme can also activate expression of antioxidant and globin genes. Heme binds to the transcription factor BACH1, which represses NRF2-mediated gene transcription. ASP8731, is a selective small molecule inhibitor of BACH1. We investigated the ability of ASP8731 to modulate pathways involved in SCD pathophysiology. In HepG2 liver cells, ASP8731 increased HMOX1 and FTH1 mRNA. In pulmonary endothelial cells, ASP8731 decreased VCAM1 mRNA in response to TNF-α and blocked a decrease in glutathione in response to hemin. Townes-SS mice were gavaged once per day for 4 weeks with ASP8731, hydroxyurea (HU) or vehicle. Both ASP8731 and HU inhibited heme-mediated microvascular stasis and in combination, ASP8731 significantly reduced microvascular stasis compared to HU alone. In Townes-SS mice, ASP8731 and HU markedly increased heme oxygenase-1 and decreased hepatic ICAM-1, NF-kB phospho-p65 protein expression in the liver, and white blood cell counts. In addition, ASP8731 increased gamma-globin expression and HbF+ cells (F-cells) as compared to vehicle-treated mice. In human erythroid differentiated CD34+ cells, ASP8731 increased HGB mRNA and increased the percentage of F-cells 2-fold in manner similar to HU. ASP8731 and HU when given together induced more HbF+ cells compared to either drug alone. In CD34+ cells from one donor that was non-responsive to HU, ASP8731 induced HbF+ cells ~2-fold. ASP8731 and HU also increased HBG and HBA, but not HBB mRNA in erythroid differentiated CD34+ cells derived from SCD patients. These data indicate that BACH1 may offer a new therapeutic target to treat SCD.

Protocol for "Genetic composition of sickle cell disease in the Arab population: A systematic review"

Background

Sickle Cell Disease (SCD) is a global health issue in hematology with a progressively increasing prevalence. There are recent advances in the management of SCD, with new drugs being introduced. It is essential to analyze the genetic makeup of SCD regionally to anticipate the effectiveness of management modalities. This systematic review's main objectives are (a) to combine the existing knowledge of the genetic composition of SCD in the Arab population and (b) to analyze the various phenotypes of SCD prevalent in the Arab population.

Methods

We will perform a systematic review and search multiple electronic databases predefined search terms to identify eligible articles. Eligible studies should report findings on the genetic testing of Sickle Cell disease in the 22 Arab countries. Case reports, case series, observational studies with cross‐sectional or prospective research design, case‐control studies, and experimental studies will be included. Study quality will be independently evaluated by two reviewers using the statistical methodology and categories guided by the Cochrane Collaboration Handbook and PRISMA guidelines.

Discussion

This review will explore and integrate the evidence available on the various genotypes and phenotypes of SCD in the Arab population. By acquiring and summarizing data about the genetic and phenotypic variants of the SCD patient population, this study will add to the knowledge and help find more precise treatments.

Systematic review registration

The protocol is registered at the International Prospective Register of Systematic Reviews (PROSPERO; registration number: CRD42020218666).

Haem oxygenase-1 and haemopexin gene polymorphisms and the risk of anti-tuberculosis drug-induced hepatotoxicity in China

Objective: To assess whether the risk of anti-tuberculosis drug-induced hepatotoxicity (ATDH) might be influenced by haem oxygenase-1 (HMOX1) and haemopexin (HPX) gene polymorphisms. Methods: A dynamic anti-tuberculosis treatment cohort was constructed, and the 1:4 matched nested case-control study was analysed. Eight single nucleotide polymorphisms (SNPs) of the two genes were selected for genotyping and Bonferroni correction was performed to correct for multiple comparison. Results: Overall, 7.8% of patients developed ATDH. SNP rs1807714 in the HMOX1 gene had decreased effects on the risk of moderate and severe hepatotoxicity under the dominant and additive models, and hepatocellular injury under the additive model. SNP rs2682099 in the HPX gene had increased effects on the risk of moderate and severe hepatotoxicity under the recessive model. However, these associations disappeared after Bonferroni correction. Conclusion: HMOX1 and HPX gene polymorphisms might not be associated with susceptibility to ATDH in the Chinese population.

Serum Level of High-Mobility Group Box Protein 1 as a Potential Treatment Target in Egyptian Sickle Cell Disease Patients

Background: During tissue injury, high mobility group box 1 (HMGB1) is passively released from necrotic cells and actively secreted by inflammatory cells. Extracellular HMGB1 acts as an amplifier of Toll-Like Receptor (TLR)-dependent inflammation rather than a primary trigger of inflammation. We studied HMGB1 quantitative trait locus reference sequence 2249825 (rs2249825) and its serum level in both sickle cell disease (SCD) patients and healthy subjects to explore its possible role in the pathogenesis of vaso-occlusive crises (VOCs). Methods: HMGB1 rs2249825 was assayed in peripheral blood samples using real-time polymerase chain reaction (RT-PCR). While the serum level was assayed using a two-site enzyme-linked immunosorbent technique (ELISA). Results: Both the SCD patients and the control group had comparable HMGB1 rs2249825 genotype frequencies (P-value >0.05). SCD patients at their steady-state showed statistically significantly higher serum HMGB1 levels than the healthy controls, a median of 0.6 ng/ml with a range of 0.1- 85 ng/ml versus a median of 0.3 ng/ml and a range of 0.1-3 ng/ml (P-value <0.001), respectively. Statistically significant skewed high serum HMGB1 in the VOC samples in contrast to the steady-state samples was observed in the SCD patients with a median of 3.2 ng/ml and a range of 0.3-76.4 ng/ml versus a median of 0.2 ng/ml and a range 0.2-7.4 ng/ml (P-value <0.0001), respectively.     Conclusion: HMGB1 could have a role in the VOC pathogenesis, hence it is suggested as a potential additive therapeutic target in SCD in general and in vaso-occlusions in specific. Keywords: Sickle cell disease, HMGB1, Hemoglobin S

Epidemiology of Stroke in Sickle Cell Disease

Sickle cell disease is the most common cause of stroke in childhood, both ischaemic and haemorrhagic, and it also affects adults with the condition. Without any screening or preventative treatment, the incidence appears to fall within the range 0.5 to 0.9 per 100 patient years of observation. Newborn screening with Penicillin prophylaxis and vaccination leading to reduced bacterial infection may have reduced the incidence, alongside increasing hydroxyurea prescription. Transcranial Doppler screening and prophylactic chronic transfusion for at least an initial year has reduced the incidence of stroke by up to 10-fold in children with time averaged mean of the maximum velocity >200 cm/s. Hydroxyurea also appears to reduce the incidence of first stroke to a similar extent in the same group but the optimal dose remains controversial. The prevention of haemorrhagic stroke at all ages and ischaemic stroke in adults has not yet received the same degree of attention. Although there are fewer studies, silent cerebral infarction on magnetic resonance imaging (MRI), and other neurological conditions, including headache, epilepsy and cognitive dysfunction, are also more prevalent in sickle cell disease compared with age matched controls. Clinical, neuropsychological and quantitative MRI screening may prove useful for understanding epidemiology and aetiology.

Significance of heme oxygenase-1(HMOX1) gene on fetal hemoglobin induction in sickle cell anemia patients

Though the patients with sickle cell anemia (SCA) inherit same genetic mutation, they show considerable phenotypic heterogeneity. It has been observed that patients with elevated fetal hemoglobin (HbF) levels have a relatively mild clinical course. There is sparse literature on the association of higher HbF levels leading to reduction in the oxidative stress in SCA patients. Hence in this study, the significance between the HMOX1 gene polymorphisms and the HbF levels has been studied. Preliminary screening was carried out. Genotyping of 3 variants in the HMOX1 gene was performed in 90 SCA patients and 50 healthy controls by PCR–RFLP, GeneScan and direct DNA sequencing. It was observed that SCA patients with higher HbF levels, showed improved hematological indices with an inverse effect on HbS levels. The TT genotype of rs2071746 (A→T) polymorphism was found to be associated with elevated HbF levels (P: 0.012). Also, the long form (> 25 GT repeats) of rs3074372 (GT)n repeats was found to be linked with increased HbF levels. We could not find any association of rs2071749 (A→G) polymorphism with the HbF levels. As, the sickle cell anemia patients show significant oxidative stress due to hemolysis, the study of polymorphisms in the HMOX1 gene may act as a potential independent marker for elevated HbF levels.

CCR5-Δ32 gene variant frequency in the Turkish Cypriot population

Recent UNAIDS reports (December 2019) indicate that 37.9 million people have been affected by HIV infection around the globe in 2018, of which 1.7 million are cited as new infections. Human immunodeficiency virus-1 (HIV-1) requires both the CD4 receptor, as the primary receptor, and a chemokine co-receptor to gain entry into the cell. In addition to the WT allele for C–C motif chemokine receptor 5 (CCR5-wt), there is another allele with a 32 bp deletion in the protein coding region (CCR5-Δ32). Individuals who are homozygous for the mutant allele are resistant towards M-tropic HIV infections. In the current study, we aimed to determine the CCR5-Δ32 allele frequency in the Turkish Cypriot population with 326 subjects, 141 men (43.1%) and 185 (56.9%) women. The region of the CCR5 gene containing the Δ32 deletion was amplified using flanking primers. The CCR5 gene Δ32 allele frequency was calculated at 3% and only observed in heterozygous individuals. We hope that our current publication could be a point of dialog between the physicians, the government officials and the public set up a more modern and well-structured HIV screening program in an effort to control and hopefully eliminate HIV from the Turkish Cypriot population.

Sickle cell trait and the potential risk of severe coronavirus disease 2019-A mini-review

Coronavirus Disease 2019 (COVID‐19) pandemic is a rapidly evolving public health problem. The severity of COVID‐19 cases reported hitherto has varied greatly from asymptomatic to severe pneumonia and thromboembolism with subsequent mortality. An improved understanding of risk factors for adverse clinical outcomes may shed some light on novel personalized approaches to optimize clinical care in vulnerable populations. Emerging trends in the United States suggest possibly higher mortality rates of COVID‐19 among African Americans, although detailed epidemiological study data is pending. Sickle cell disease (SCD) disproportionately affects Black/African Americans in the United States as well as forebearers from sub‐Saharan Africa, the Western Hemisphere (South America, the Caribbean, and Central America), and some Mediterranean countries. The carrier frequency for SCD is high among African Americans. This article underscores the putative risks that may be associated with COVID‐19 pneumonia in sickle cell trait as well as potential opportunities for individualized medical care in the burgeoning era of personalized medicine.

Polymorphisms in the heme oxygenase-1 and bone morphogenetic protein receptor type 1b genes and estimated glomerular filtration rate in Brazilian sickle cell anemia patients

INTRODUCTION

Mutations affecting genes involved in oxidative and signaling pathways may be associated with kidney disease in sickle cell anemia. We determined the allele and genotype frequencies of some polymorphisms in the promoter regions of the Heme Oxygenase-1 (HMOX1) [rs2071746 (A>T) and (GT)n repeats, short (S) and long (L) alleles] and Bone Morphogenetic Protein Receptor type-1B (BMPR1B) [rs17022863 (A>G), rs4331783 (A>G) and rs1470409 (A>G)] genes in 75 adult patients with sickle cell anemia and 160 healthy controls and investigated whether these polymorphisms may influence the estimated glomerular filtration rate for the patients.

METHODS

The single nucleotide polymorphisms were genotyped using the TaqMan assays, the HMOX1(GT)n repeats were determined by polymerase chain reaction fragment size analysis and the estimated glomerular filtration rate was calculated by the Modification of Diet in Renal Disease formula.

RESULTS

Regarding the HMOX1rs2071746, the estimated glomerular filtration rate median was significantly higher in TT patients (p=0.019), including when TT was compared with AT+AA (p=0.009); for the (GT)n repeats, the estimated glomerular filtration rate medians of SS, SL and LL significantly differed (p=0.009), being the LL estimated glomerular filtration rate median significantly higher, when compared with the LS+SS (p=0.005). These results suggest that both the homozygotes, TT for rs2071746 and LL for (GT)n repeats, lead to a higher risk of developing renal complications. Concerning the BMPR1B, the frequencies of GG for rs17022863 and AA for rs4331783 were significantly higher in patients than in controls (p=0.002 and p=0.008, respectively), however no association with estimated glomerular filtration rate was found.

CONCLUSION

These results contribute to a better understanding of the genetic factors related to the development of nephropathy in sickle cell anemia patients.