Transcranial doppler velocity in iron-deficient Nigerian children with sickle cell anemia.

Oral iron supplementation in iron deficient children with sickle cell anemia and normal transcranial Doppler ultrasound (TCD) velocities does not reduce arterial flow in the middle cerebral artery.

Germinal centre hypoxia and regulation of antibody qualities by a hypoxia response system.

Germinal centres (GCs) promote humoral immunity and vaccine efficacy. In GCs, antigen-activated B cells proliferate, express high-affinity antibodies, promote antibody class switching, and yield B cell memory. Whereas the cytokine milieu has long been known to regulate effector functions that include the choice of immunoglobulin class, both cell-autonomous and extrinsic metabolic programming have emerged as modulators of T-cell-mediated immunity. Here we show in mice that GC light zones are hypoxic, and that low oxygen tension () alters B cell physiology and function. In addition to reduced proliferation and increased B cell death, low impairs antibody class switching to the pro-inflammatory IgG2c antibody isotype by limiting the expression of activation-induced cytosine deaminase (AID). Hypoxia induces HIF transcription factors by restricting the activity of prolyl hydroxyl dioxygenase enzymes, which hydroxylate HIF-1α and HIF-2α to destabilize HIF by binding the von Hippel-Landau tumour suppressor protein (pVHL). B-cell-specific depletion of pVHL leads to constitutive HIF stabilization, decreases antigen-specific GC B cells and undermines the generation of high-affinity IgG, switching to IgG2c, early memory B cells, and recall antibody responses. HIF induction can reprogram metabolic and growth factor gene expression. Sustained hypoxia or HIF induction by pVHL deficiency inhibits mTOR complex 1 (mTORC1) activity in B lymphoblasts, and mTORC1-haploinsufficient B cells have reduced clonal expansion, AID expression, and capacities to yield IgG2c and high-affinity antibodies. Thus, the normal physiology of GCs involves regional variegation of hypoxia, and HIF-dependent oxygen sensing regulates vital functions of B cells. We propose that the restriction of oxygen in lymphoid organs, which can be altered in pathophysiological states, modulates humoral immunity.

Peripheral tolerance can be modified by altering KLF2-regulated Treg migration.

Tregs are essential for maintaining peripheral tolerance, and thus targeting these cells may aid in the treatment of autoimmunity and cancer by enhancing or reducing suppressive functions, respectively. Before these cells can be harnessed for therapeutic purposes, it is necessary to understand how they maintain tolerance under physiologically relevant conditions. We now report that transcription factor Kruppel-like factor 2 (KLF2) controls naive Treg migration patterns via regulation of homeostatic and inflammatory homing receptors, and that in its absence KLF2-deficient Tregs are unable to migrate efficiently to secondary lymphoid organs (SLOs). Diminished Treg trafficking to SLOs is sufficient to initiate autoimmunity, indicating that SLOs are a primary site for maintaining peripheral tolerance under homeostatic conditions. Disease severity correlates with impaired Treg recruitment to SLOs and, conversely, promotion of Tregs into these tissues can ameliorate autoimmunity. Moreover, stabilizing KLF2 expression within the Treg compartment enhances peripheral tolerance by diverting these suppressive cells from tertiary tissues into SLOs. Taken together, these results demonstrate that peripheral tolerance is enhanced or diminished through modulation of Treg trafficking to SLOs, a process that can be controlled by adjusting KLF2 protein levels.

Functional interactions between Lmo2, the Arf tumor suppressor, and Notch1 in murine T-cell malignancies.

LMO2 is a target of chromosomal translocations in T-cell tumors and was activated by retroviral vector insertions in T-cell tumors from X-SCID patients in gene therapy trials. To better understand the cooperating genetic events in LMO2-associated T-cell acute lymphoblastic leukemia (T-ALL), we investigated the roles of Arf tumor suppressor loss and Notch activation in murine models of transplantation. Lmo2 overexpression enhanced the expansion of primitive DN2 thymocytes, eventually facilitating the stochastic induction of clonal CD4(+)/CD8(+) malignancies. Inactivation of the Arf tumor suppressor further increased the self-renewal capacity of the primitive, preleukemic thymocyte pool and accelerated the development of aggressive, Lmo2-induced T-cell lympholeukemias. Notch mutations were frequently detected in these Lmo2-induced tumors. The Arf promoter was not directly engaged by Lmo2 or mutant Notch, and use of a mouse model in which activation of a mutant Notch allele depends on previous engagement of the Arf promoter revealed that Notch activation could occur as a subsequent event in T-cell tumorigenesis. Therefore, Lmo2 cooperates with Arf loss to enhance self-renewal in primitive thymocytes. Notch mutation and Arf inactivation appear to independently cooperate in no requisite order with Lmo2 overexpression in inducing T-ALL, and all 3 events remained insufficient to guarantee immediate tumor development.

A feasibility randomized controlled trial of an mHealth app vs booklets for patient-facing guidelines in adults with SCD.

Despite the increased number of evidence-based guidelines for sickle cell disease (SCD), dissemination of evidence-based guidelines in lay language for individuals or families with SCD has not been evaluated. We conducted a feasibility randomized controlled trial to determine the acceptability of a mobile health (mHealth) app with patient-facing guidelines to improve the knowledge of individuals with SCD about SCD-specific knowledge and reduce hospitalizations. Primary outcome measures include recruitment, retention, and adherence rates. Adults with SCD were enrolled at 2 sickle cell centers between 2018 and 2022. Participants were randomized to receive either an mHealth app + booklet with patient-facing guidelines or a booklet with the guidelines alone. Participants completed surveys at baseline and a final 6-month visit. Approximately 67 of 74 (91%) agreed to participate and were randomized, with 50 of 67 (75%) completing all the study components. All participants who completed the study in the treatment arm used the app. Our results demonstrated high recruitment, retention, and adherence rate for the first randomized trial for an mHealth app with patient-facing guidelines in adults with SCD. This clinical trial was registered at https://www.clinicaltrials.gov/ as #NCT03629678.

The impact of in utero transfusions on perinatal outcomes in patients with alpha thalassemia major: the UCSF registry.

Alpha thalassemia major (ATM) is a hemoglobinopathy that usually results in perinatal demise if in utero transfusions (IUTs) are not performed. We established an international registry (NCT04872179) to evaluate the impact of IUTs on survival to discharge (primary outcome) as well as perinatal and neurodevelopmental secondary outcomes. Forty-nine patients were diagnosed prenatally, 11 were diagnosed postnatally, and all 11 spontaneous survivor genotypes had preserved embryonic zeta-globin levels. We compared 3 groups of patients; group 1, prenatally diagnosed and alive at hospital discharge (n = 14), group 2, prenatally diagnosed and deceased perinatally (n = 5), and group 3, postnatally diagnosed and alive at hospital discharge (n = 11). Group 1 had better outcomes than groups 2 and 3 in terms of the resolution of hydrops, delivery closer to term, shorter hospitalizations, and more frequent average or greater neurodevelopmental outcomes. Earlier IUT initiation was correlated with higher neurodevelopmental (Vineland-3) scores (r = -0.72, P = .02). Preterm delivery after IUT was seen in 3/16 (19%) patients who continued their pregnancy. When we combined our data with those from 2 published series, patients who received ≥2 IUTs had better outcomes than those with 0 to 1 IUT, including resolution of hydrops, delivery at ≥34 weeks gestation, and 5-minute appearance, pulse, grimace, activity, and respiration scores ≥7. Neurodevelopmental assessments were normal in 17/18 of the ≥2 IUT vs 5/13 of the 0 to 1 IUT group (OR 2.74; P = .01). Thus, fetal transfusions enable the survival of patients with ATM and normal neurodevelopment, even in those patients presenting with hydrops. Nondirective prenatal counseling for expectant parents should include the option of IUTs.

Long-Term Health Effects of Curative Therapies on Heart, Lungs, and Kidneys for Individuals with Sickle Cell Disease Compared to Those with Hematologic Malignancies.

The goal of curing children and adults with sickle cell disease (SCD) is to maximize benefits and minimize intermediate and long-term adverse outcomes so that individuals can live an average life span with a high quality of life. While greater than 2000 individuals with SCD have been treated with curative therapy, systematic studies have not been performed to evaluate the long-term health effects of hematopoietic stem cell transplant (HSCT) in this population. Individuals with SCD suffer progressive heart, lung, and kidney disease prior to curative therapy. In adults, these sequalae are associated with earlier death. In comparison, individuals who undergo HSCT for cancer are heavily pretreated with chemotherapy, resulting in potential acute and chronic heart, lung, and kidney disease. The long-term health effects on the heart, lung, and kidney for children and adults undergoing HSCT for cancer have been extensively investigated. These studies provide the best available data to extrapolate the possible late health effects after curative therapy for SCD. Future research is needed to evaluate whether HSCT abates, stabilizes, or exacerbates heart, lung, kidney, and other diseases in children and adults with SCD receiving myeloablative and non-myeloablative conditioning regimens for curative therapy.

Stage-specific Arf tumor suppression in Notch1-induced T-cell acute lymphoblastic leukemia.

Frequent hallmarks of T-cell acute lymphoblastic leukemia (T-ALL) include aberrant NOTCH signaling and deletion of the CDKN2A locus, which contains 2 closely linked tumor suppressor genes (INK4A and ARF). When bone marrow cells or thymocytes transduced with a vector encoding the constitutively activated intracellular domain of Notch1 (ICN1) are expanded ex vivo under conditions that support T-cell development, cultured progenitors rapidly induce CD4+/CD8+ T-ALLs after infusion into healthy syngeneic mice. Under these conditions, enforced ICN1 expression also drives formation of T-ALLs in unconditioned CD-1 nude mice, bypassing any requirements for thymic maturation. Retention of Arf had relatively modest activity in suppressing the formation of T-ALLs arising from bone marrow-derived ICN1+ progenitors in which the locus is epigenetically silenced, and all resulting Arf (+/+) tumors failed to express the p19(Arf) protein. In striking contrast, retention of Arf in thymocyte-derived ICN1+ donor cells significantly delayed disease onset and suppressed the penetrance of T-ALL. Use of cultured thymocyte-derived donor cells expressing a functionally null Arf-GFP knock-in allele confirmed that ICN1 signaling can induce Arf expression in vivo. Arf activation by ICN1 in T cells thereby provides stage-specific tumor suppression but also a strong selective pressure for deletion of the locus in T-ALL.

COVID-19 pneumonia in a pediatric sickle cell patient requiring red blood cell exchange.

Patients with sickle cell disease are already at high risk for respiratory complications, which SARS-CoV-2 can rapidly worsen. The case emphasizes the importance of efficiently maximizing standard therapies in sickle cell patients with COVID-19.

Adapting medical guidelines to be patient-centered using a patient-driven process for individuals with sickle cell disease and their caregivers.

BACKGROUND: Evidence-based guidelines for sickle cell disease (SCD) health maintenance and management have been developed for primary health care providers, but not for individuals with SCD. To improve the quality of care delivered to individuals with SCD and their caregivers, the main purposes of this study were to: (1) understand the desire for patient-centered guidelines among the SCD community; and (2) adapt guideline material to be patient-centered using community-engagement strategies involving health care providers, community -based organizations, and individuals with the disease. METHODS: From May-December 2016, a volunteer sample of 107 individuals with SCD and their caregivers gave feedback at community forums (n = 64) and community listening sessions (n = 43) about technology use for health information and desire for SCD-related guidelines. A team of community research partners consisting of community stakeholders, individuals living with SCD, and providers and researchers (experts) in SCD at nine institutions adapted guidelines to be patient-centered based on the following criteria: (1) understandable, (2) actionable, and (3) useful. RESULTS: In community forums (n = 64), almost all participants (91%) wanted direct access to the content of the guidelines. Participants wanted guidelines in more than one format including paper (73%) and mobile devices (79%). Guidelines were adapted to be patient-centered. After multiple iterations of feedback, 100% of participants said the guidelines were understandable, most (88%) said they were actionable, and everyone (100%) would use these adapted guidelines to discuss their medical care with their health care providers. CONCLUSIONS: Individuals with SCD and their caregivers want access to guidelines through multiple channels, including technology. Guidelines written for health care providers can be adapted to be patient-centered using Community-engaged research involving providers and patients. These patient-centered guidelines provide a framework for patients to discuss their medical care with their health care providers.

Epigenetic regulation of the Ink4a-Arf (Cdkn2a) tumor suppressor locus in the initiation and progression of Notch1-driven T cell acute lymphoblastic leukemia.

Activating mutations of NOTCH1 and deletion of the INK4A-ARF (CDKN2A) tumor suppressor locus are two of the most frequent genetic alterations in T cell acute lymphoblastic leukemia (T-ALL). In a murine model of T-ALL induced by the intracellular domain of Notch1 (ICN1), the genetic interaction between ICN1 signaling and Arf inactivation is developmentally stage-specific, with a more pronounced requirement for Arf deletion in thymocytes than in bone marrow precursors targeted for transformation. In the thymus, the target cell for transformation is a CD4 and CD8 double-negative progenitor that undergoes T cell receptor beta-chain rearrangement, a cell type in which polycomb silencing of Ink4a-Arf is normally requisite. Epigenetic remodeling during tumor progression licenses Arf as a tumor suppressor and in turn provides the selective pressure for Ink4a-Arf deletion in clonal T-ALLs that emerge.

Vital roles of mTOR complex 2 in Notch-driven thymocyte differentiation and leukemia.

Notch plays critical roles in both cell fate decisions and tumorigenesis. Notch receptor engagement initiates signaling cascades that include a phosphatidylinositol 3-kinase/target of rapamycin (TOR) pathway. Mammalian TOR (mTOR) participates in two distinct biochemical complexes, mTORC1 and mTORC2, and the relationship between mTORC2 and physiological outcomes dependent on Notch signaling is unknown. In this study, we report contributions of mTORC2 to thymic T-cell acute lymphoblastic leukemia (T-ALL) driven by Notch. Conditional deletion of Rictor, an essential component of mTORC2, impaired Notch-driven proliferation and differentiation of pre-T cells. Furthermore, NF-κB activity depended on the integrity of mTORC2 in thymocytes. Active Akt restored NF-κB activation, a normal rate of proliferation, and differentiation of Rictor-deficient pre-T cells. Strikingly, mTORC2 depletion lowered CCR7 expression in thymocytes and leukemic cells, accompanied by decreased tissue invasion and delayed mortality in T-ALL driven by Notch. Collectively, these findings reveal roles for mTORC2 in promoting thymic T cell development and T-ALL and indicate that mTORC2 is crucial for Notch signaling to regulate Akt and NF-κB.