Sickle cell disease; An overview of the disease and its systemic effects

The Association Between Dental Caries and Salivary Buffering Capacity in Syrian Patients Diagnosed with Sickle Cell Disease

Background Sickle cell disease (SCD) is a genetic disorder caused by mutations in the HBB gene, resulting in the abnormal shape of red blood cells. This condition is accompanied by various oral manifestations including salivary gland dysfunction leading to a heightened susceptibility to dental caries. This disorder is primarily treated with hydroxyurea. This study aims to assess dental caries utilizing the decay, missing, filling teeth (DMFT) index and evaluate salivary buffering capacity in patients diagnosed with SCD (HbSS type). The study also aims to assess the relationship between DMFT and salivary buffering capacity. Additionally, the study aimed to find a correlation between treatment with hydroxyurea and changes in both dental caries and salivary buffering capacity. Methods This case-control study enrolled a total of 100 participants aged between 20 and 50 years. The participants were divided into two groups: the study group, which comprised 70 individuals diagnosed with SCD (HbSS type), who were asked to report their current use of hydroxyurea, and the control group, which included 30 healthy individuals. Dental caries were assessed using the DMFT index, while salivary buffering capacity was measured using a pH meter model 420A device. Results The study group exhibited a mean DMFT index value of 6.39 compared to 5.20 in the control group. This difference was statistically significant (P-value=0.037), indicating higher DMFT values among patients with SCD. Salivary buffering capacity was significantly lower in the study group compared to the control group, with average values of 6.47 and 6.88, (P-value=.022). Interestingly, the administration of hydroxyurea impacted salivary buffering capacity, resulting in lower values for individuals using the drug (P-value=0.039). Conversely, hydroxyurea did not have a significant effect on DMFT values (P-value=0.317). Conclusion SCD increases susceptibility to dental caries and is associated with significant changes in salivary composition. At the same time, the potential negative impact of hydroxyurea is acknowledged.

X-ray crystallography and sickle cell disease drug discovery-a tribute to Donald Abraham

X-ray crystallography and structure-based drug discovery have played a major role in the discovery of antisickling agents that target hemoglobin (Hb) for the treatment of sickle cell disease (SCD). Sickle cell disease, the most common inherited hematologic disorder, occurs as a result of a single point mutation of βGlu6 in normal human adult hemoglobin (HbA) to βVal6 in sickle hemoglobin (HbS). The disease is characterized by polymerization of HbS and sickling of red blood cells (RBCs), leading to several secondary pathophysiologies, including but not limited to vaso-occlusion, hemolytic anemia, oxidative stress, inflammation, stroke, pain crisis, and organ damage. Despite the fact that SCD was the first disease to have its molecular basis established, the development of therapies was for a very long time a challenge and took several decades to find therapeutic agents. The determination of the crystal structure of Hb by Max Perutz in the early 60s, and the pioneering X-ray crystallography research by Donald J. Abraham in the early 80s, which resulted in the first structures of Hb in complex with small molecule allosteric effectors of Hb, gave much hope that structure-based drug discovery (SBDD) could be used to accelerate development of antisickling drugs that target the primary pathophysiology of hypoxia-induced HbS polymerization to treat SCD. This article, which is dedicated to Donald J. Abraham, briefly reviews structural biology, X-ray crystallography and structure-based drug discovery from the perspective of Hb. The review also presents the impact of X-ray crystallography in SCD drug development using Hb as a target, emphasizing the major and important contributions by Don Abraham in this field.

Modulating hemoglobin allostery for treatment of sickle cell disease: current progress and intellectual property

INTRODUCTION

Sickle cell disease (SCD) is a debilitating inherited disorder that affects millions worldwide. Four novel SCD therapeutics have been approved, including the hemoglobin (Hb) modulator Voxelotor.

AREAS COVERED

This review provides an overview of discovery efforts toward modulating Hb allosteric behavior as a treatment for SCD, with a focus on aromatic aldehydes that increase Hb oxygen affinity to prevent the primary pathophysiology of hypoxia-induce erythrocyte sickling.

EXPERT OPINION

The quest to develop small molecules, especially aromatic aldehydes, to modulate Hb allosteric properties for SCD began in the 1970s; however, early promise was dogged by concerns that stalled support for research efforts. Persistent efforts eventually culminated in the discovery of the anti-sickling agent 5-HMF in the 2000s, and reinvigorated interest that led to the discovery of vanillin analogs, including Voxelotor, the first FDA approved Hb modulator for the treatment of SCD. With burgeoning interest in the field of Hb modulation, there is a growing landscape of intellectual property, including drug candidates at various stages of preclinical and clinical investigations. Hb modulators could provide not only the best chance for a highly effective oral therapy for SCD, especially in the under-developed world, but also a way to treat a variety of other human conditions.

Advances in Sickle Cell Disease Treatments

Sickle Cell Disease (SCD) is an inherited disorder of red blood cells that is caused by a single mutation in the β -globin gene. The disease, which afflicts millions of patients worldwide mainly in low income countries, is characterized by high morbidity, mortality and low life expectancy. The new pharmacological and non-pharmacological strategies for SCD is urgent in order to promote treatments able to reduce patient's suffering and improve their quality of life. Since the FDA approval of HU in 1998, there have been few advances in discovering new drugs; however, in the last three years voxelotor, crizanlizumab, and glutamine have been approved as new therapeutic alternatives. In addition, new promising compounds have been described to treat the main SCD symptoms. Herein, focusing on drug discovery, we discuss new strategies to treat SCD that have been carried out in the last ten years to discover new, safe, and effective treatments. Moreover, non-pharmacological approaches, including red blood cell exchange, gene therapy and hematopoietic stem cell transplantation will be presented.

Intentional and unintentional nonadherence to hydroxyurea among people with sickle cell disease: a qualitative study

Hydroxyurea is an efficacious treatment for sickle cell disease (SCD), but adoption is low among individuals with SCD. The objective of this study was to examine barriers to patients' adherence to hydroxyurea use regimens by using the intentional and unintentional medication nonadherence framework. We interviewed individuals with SCD age 15 to 49.9 years who were participants in the Sickle Cell Disease Implementation Consortium (SCDIC) Needs Assessment. The intentional and unintentional medication nonadherence framework explains barriers to using hydroxyurea and adds granularity to the understanding of medication adherence barriers unique to the SCD population. In total, 90 semi-structured interviews were completed across 5 of the 8 SCDIC sites. Among interviewed participants, 57.8% (n = 52) were currently taking hydroxyurea, 28.9% (n = 26) were former hydroxyurea users at the time of the interview, and 13.3% (n = 12) had never used hydroxyurea but were familiar with the medication. Using a constructivist grounded theory approach, we discovered important themes that contributed to nonadherence to hydroxyurea, which were categorized under unintentional (eg, Forgetfulness, External Influencers) and intentional (Negative Perceptions of Hydroxyurea, Aversion to Taking Any Medications) nonadherence types. Participants more frequently endorsed adherence barriers that fell into the unintentional nonadherence type (70%) vs intentional nonadherence type (30%). Results from this study will help SCD health care providers understand patient choices and decisions as being either unintentional or intentional, guide tailored clinical discussions regarding hydroxyurea therapy, and develop specific, more nuanced interventions to address nonadherence factors.

Descriptive analysis of sickle cell patients living in France: The PHEDRE cross-sectional study

Background

Sickle cell disease (SCD) induces chronic haemolytic anaemia and intermittent vaso-occlusion that results in tissue ischaemia causing acute, severe pain episodes that can lead to frequent hospitalizations. These consequences can have repercussions on family, social, school and/or professional life. Here, we present some of the results of the PHEDRE study (Pharmacodépendance Et DREpanocytose—drug dependence and sickle-cell disease), which is the largest study of patients with SCD in France. This paper intends to describe characteristics of the French SCD population. We also aimed to assess the impact of the disease on the lives of patients using objective and subjective variables.

Methods

The PHEDRE study was a national multicentric observational study. Adults, adolescents and children with a confirmed SCD diagnosis were included in the study by their referring doctor. Then, they were interviewed by phone about their socioeconomic status, about the impact of the disease on their lives and about their analgesic and psychoactive drug use.

Results

The study population consisted of 872 patients (28% were minors). Seventy-two percent of adults were active, and all minors were in school. Many patients presented criteria of severe SCD. Seventy-five percent were homozygous SS, 15% were double heterozygotes SC and 8% were heterozygotes Sβthal, 87% received specific treatment, 58% were hospitalized at least once for vaso-occlusive crisis in the past 12 months, and the number of analgesic drugs taken averaged 3.8. Seventy-five percent of patients reported academic or professional consequences related to their SCD, and 52% reported social consequences.

Conclusions

The impact of SCD on patients’ lives can be significant, nevertheless their social integration seems to be maintained. We highlighted respect of recommendations regarding analgesic treatments and only a few patients used tobacco, alcohol or cannabis.

Trial registration

Clinical Trials, NCT02580565; https://clinicaltrials.gov/ Registered 16 October 2015.

Bone fragility in patients affected by congenital diseases non skeletal in origin

BACKGROUND

Bone tissue represents a large systemic compartment of the human body, with an active metabolism, that controls mineral deposition and removal, and where several factors may play a role. For these reasons, several non-skeletal diseases may influence bone metabolism. It is of a crucial importance to classify these disorders in order to facilitate diagnosis and clinical management. This article reports a taxonomic classification of non-skeletal rare congenital disorders, which have an impact on bone metabolism METHODS: The International Osteoporosis Foundation (IOF) Skeletal Rare Diseases Working Group (SRD-WG), comprised of basic and clinical scientists, has decided to review the taxonomy of non-skeletal rare disorders that may alter bone physiology.

RESULTS

The taxonomy of non-skeletal rare congenital disorders which impact bone comprises a total of 6 groups of disorders that may influence the activity of bone cells or the characteristics of bone matrix.

CONCLUSIONS

This paper provides the first comprehensive taxonomy of non-skeletal rare congenital disorders with impact on bone physiology.

Predictors of dental complications post-dental treatment in patients with sickle cell disease

Objective

Our aim was to explore potential medical or dental indicators associated with dental complications and the utilization of emergency services in sickle cell disease (SCD), especially that clinical reports on adverse outcomes post‐dental treatment are scarce.

Materials and methods

A retrospective analysis of dental treatments of 47 eligible adults with confirmed SCD between May 2016 and October 2019. Logistic regression analysis was used whether clinical outcomes, course of dental treatment, and regularity of dental care are associated with dental complications after dental procedures and/or resulted in emergency care or hospital admissions.

Results

We identified a new, statistically significant association (p‐value = .01) between the number of prescription medications taken and complications (10%) after dental procedures. The most frequent dental procedures were tooth extractions (36%) and pain management (28%) during a non‐scheduled dental encounter (68%). The majority of cases did not participate in regular recall exams and periodical oral hygiene maintenance.

Conclusions

A higher number of prescription medications was associated with an increased risk of post‐dental complications in SCD patients. A thorough medical history, including a list of prescribed medications, and collaboration with the patient medical team are important to assess the risk of complications post‐dental procedures and the need for antibiotic prophylaxis according to the case complexity.

A Meta-Analysis on the Seroprevalence of Parvovirus B19 among Patients with Sickle Cell Disease

Background

Parvovirus B19 (B19 V) infection had been reported to be more frequent with serious clinical outcomes in patients with sickle cell disease (SCD) than in the general population. There is a wide variation in data among the existing literature regarding the seroprevalence of B19 V in patients with SCD. These data require further summary and analyses for better accuracy. This systematic review and meta-analysis was done to estimate the seroprevalence of B19 V in patients with SCD.

Methods

This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The databases of MEDLINE/PubMed, Virtual Health Library (VHL), ScienceDirect, Google Scholar, and OpenGrey were used for the systematic search. The random-effects model was used to estimate the pooled prevalence with the corresponding 95% confidence interval (CI) using OpenMeta Analyst software. Publication bias was estimated based on Begg's test, Egger's test, and examination of the funnel plot. Subgroup analyses and metaregression were used to explore the moderators of heterogeneity between studies.

Results

A total of 18 studies including 2890 patients were analyzed. The overall IgG seroprevalence of B19 V infection among patients with SCD was found to be 48.8% (95% CI 39.5%-58.0%). Evidence of publication bias was not detected. Evidence of acute viral infection detected by positive IgM antibodies among the screened SCD patients was found in 8.30% (95% CI 5.20%-11.4%) of them. There was a statistically significant association between seroprevalence of B19 V and geographical areas.

Conclusion

There was a high prevalence of B19 V in patients with SCD. Healthcare providers need to be aware of the magnitude of B19 V infection in patients with SCD to ensure effective management. This review could provide a comprehensive view of B19 V prevalence in this susceptible population.

The National Heart, Lung, and Blood Institute Strategic Vision Implementation for Health Equity Research

The National Heart, Lung, and Blood Institute (NHLBI) provides global leadership for a research, training, and education program to promote the prevention and treatment of heart, lung, and blood diseases and enhance the health of all individuals so that they can live longer and more fulfilling lives. Inherent in this mission is the commitment to advance health equity research as an avenue for enhancing the health of all individuals. Additionally, the four goals and eight research objectives of the NHLBI Strategic Vision directly support the commitment to health equity. In this article, we present selected examples of the NHLBI Strategic Vision implementation approaches for advancing health equity research in our mission areas of heart, lung, and blood diseases. Examples of diseases for which the burden of health inequities and our strategic vision implementation approaches are discussed include hypertension, heart failure, vascular dementia, asthma, and sickle cell disease. Examples are provided of new avenues of Institute-solicited research to stimulate and address compelling scientific questions and critical challenges to advance health equity. We also highlight the emerging fields of implementation science and predictive analytics as important opportunities to accelerate the translation of discovery science into health impact for all and to advance health equity.