New Frontiers: Precise Editing of Allergen Genes Using CRISPR

Genome engineering with clustered regularly interspaced short palindromic repeats (CRISPR) technology offers the unique potential for unequivocally deleting allergen genes at the source. Compared to prior gene editing approaches, CRISPR boasts substantial improvements in editing efficiency, throughput, and precision. CRISPR has demonstrated success in several clinical applications such as sickle cell disease and β-thalassemia, and preliminary knockout studies of allergenic proteins using CRISPR editing show promise. Given the advantages of CRISPR, as well as specific DNA targets in the allergen genes, CRISPR gene editing is a viable approach for tackling allergy, which may lead to significant disease improvement. This review will highlight recent applications of CRISPR editing of allergens, particularly cat allergen Fel d 1, and will discuss the advantages and limitations of this approach compared to existing treatment options.

Hematological and Biochemical Reference Ranges for the Population with Sickle Cell Disease at Steady State in Tanzania

Hematological and biochemical reference values in sickle cell disease (SCD) are crucial for patient management and the evaluation of interventions. This study was conducted at Muhimbili National Hospital (MNH) in Dar es Salaam, Tanzania, to establish laboratory reference ranges among children and adults with SCD at steady state. Patients were grouped into five age groups and according to their sex. Aggregate functions were used to handle repeated measurements within the individual level in each age group. A nonparametric approach was used to smooth the curves, and a parametric approach was used to determine SCD normal ranges. Comparison between males and females and against the general population was documented. Data from 4422 patients collected from 2004–2015 were analyzed. The majority of the patients (35.41%) were children aged between 5–11 years. There were no significant differences (p ≥ 0.05) in mean corpuscular hemoglobin concentration (MCHC), lymphocytes, basophils, and direct bilirubin observed between males and females. Significant differences (p < 0.05) were observed in all selected parameters across age groups except with neutrophils and MCHC in adults, as well as platelets and alkaline phosphatase in infants when the SCD estimates were compared to the general population. The laboratory reference ranges in SCD at steady state were different from those of the general population and varied with sex and age. The established reference ranges for SCD at steady state will be helpful in the management and monitoring of the progress of SCD.

Influence of Haptoglobin Polymorphism on Stroke in Sickle Cell Disease Patients

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.

Heme-stress activated NRF2 skews fate trajectories of bone marrow cells from dendritic cells towards red pulp-like macrophages in hemolytic anemia

Heme is an erythrocyte-derived toxin that drives disease progression in hemolytic anemias, such as sickle cell disease. During hemolysis, specialized bone marrow-derived macrophages with a high heme-metabolism capacity orchestrate disease adaptation by removing damaged erythrocytes and heme-protein complexes from the blood and supporting iron recycling for erythropoiesis. Since chronic heme-stress is noxious for macrophages, erythrophagocytes in the spleen are continuously replenished from bone marrow-derived progenitors. Here, we hypothesized that adaptation to heme stress progressively shifts differentiation trajectories of bone marrow progenitors to expand the capacity of heme-handling monocyte-derived macrophages at the expense of the homeostatic generation of dendritic cells, which emerge from shared myeloid precursors. This heme-induced redirection of differentiation trajectories may contribute to hemolysis-induced secondary immunodeficiency. We performed single-cell RNA-sequencing with directional RNA velocity analysis of GM-CSF-supplemented mouse bone marrow cultures to assess myeloid differentiation under heme stress. We found that heme-activated NRF2 signaling shifted the differentiation of bone marrow cells towards antioxidant, iron-recycling macrophages, suppressing the generation of dendritic cells in heme-exposed bone marrow cultures. Heme eliminated the capacity of GM-CSF-supplemented bone marrow cultures to activate antigen-specific CD4 T cells. The generation of functionally competent dendritic cells was restored by NRF2 loss. The heme-induced phenotype of macrophage expansion with concurrent dendritic cell depletion was reproduced in hemolytic mice with sickle cell disease and spherocytosis and associated with reduced dendritic cell functions in the spleen. Our data provide a novel mechanistic underpinning of hemolytic stress as a driver of hyposplenism-related secondary immunodeficiency.

Laparoscopic splenectomy: how minimal can we make it?

Aims Laparoscopic splenectomy (LS) is routinely performed in children, however, a large spleen in a small child can pose significant operative challenges. We instigated a highly standardised surgical and anaesthetic approach to LS to minimise surgical trauma and enhance recovery. The aim of this study was to assess the outcomes of this programme. Methods Prospective study of all LS’s performed 2018–2021. Surgical approach was via one 10 mm and three 5 mm ports. Early hilar control was accomplished with Hem-o-loks. Splenic retrieval via the 10 mm incision used finger morcellation within an Espiner EcoSac. Anaesthesia utilised a standardised regime of agents and bupivacaine was infiltrated to the splenic bed and wound sites. Post-operative opiates were minimised. Data are presented as median [IQR]. Results Twenty consecutive children were included. Indications for LS were hereditary spherocytosis (n = 12), sickle cell disease (n = 6), beta-thalassaemia (n = 1) and splenic haemangiomatosis (n = 1). Age at surgery was 101 months [75–117] and weight 30 kg [21–37]. Splenic size was 13.4 cm [12–14.4]. Operative time was 178 min [156–185]. There were no open conversions and no significant intra or post-operative bleeding. One patient developed pancreatitis. Median post-operative pain score was 1 [1–3]. Median length of stay was 2 days [2–3]. Conclusion LS is feasible, safe and efficient in smaller children with large spleens. This standardised programme of anaesthesia and surgery based around a core team reliably results in few complications, good analgesia and short length of stay.

Effects of corticosteroids in patients with sickle cell disease and acute complications: a systematic review and meta-analysis

Whether corticosteroids improve outcome in patients with acute complications of sickle cell disease (SCD) is still debated. We performed a systematic review of the literature with the aim of estimating effects of corticosteroids on the clinical course of vaso-occlusive crisis (VOC) or acute chest syndrome (ACS) in patients with SCD. The primary outcome was transfusion requirement during hospitalization. Studies were identified by search of MEDLINE and CENTRAL database. Three randomized clinical trials (RCT) and three retrospective cohort studies (RCS) were included, involving 3,304 participants and 5,562 VOC or ACS episodes. There was no difference between corticosteroids and standard treatment regarding transfusion overall [OR=0.98 (95% CI 0.38 to 2.53)], but with a significant interaction of study type (P

Mini-review on the phyto-chemistry, pharmacology and toxicology of Cola nitida (Vent.) Schott & Endl. (Malvaceae): A medically interesting bio-resource of multiple purposes in Africa

The purpose of this mini-review was to summarize and update knowledge on the phytochemistry, pharmacology, and toxicity of <i>Cola nitida</i>, with the view of providing baseline data for herbal drug formulation. In January 2021, a non-exhaustive online search of relevant articles was carried out on the phytochemistry, pharmacology, and toxicology of <i>C. nitida</i> from scientifically well-established databases such as Science Direct, PubMed, Web of Science, Scopus, Google Scholar, and SciELO. The plant's scientific name as well as phytochemistry, pharmacology, pharmacognosy, bioactivity and toxicology were used as keywords. The chemical structures of the compounds isolated from this plant were drawn using ChemBioDraw Ultra 12.0 software. A literature survey has revealed that <i>C. nitida</i> is highly appreciated by African populations in various cultures, especially in West Africa. Phytochemical analyses showed that <i>C. nitida</i> contains interesting compounds like catechin, caffeine, epicatechin, polyphenols, alkaloids, tannins, saponins, bromelain, cardenolides, proanthocyanidins, triterpenes, glycosides, flavonoids, anthraquinones, steroids, anthocyanins, glycosides, alkaloids, etc. The presence of these phyto-compounds in the investigated plant species justifies its used as an antimicrobial, anti-malarial, anti-inflammatory, anti-diabetic, anti-coagulant agent. Thus, <i>C. nitida</i> could be used as a raw material for manufacturing efficient medication against various diseases, including sickle cell disease.