Antonio Roberto Lucena Araujo

Sickle cell anemia (SCA) is associated with a high prevalence of cerebrovascular complications, such as ischemic stroke, particularly at young ages. Among various molecules, vitamin D has been implicated in stroke occurrence. By binding to the vitamin D receptor (VDR), vitamin D regulates several mechanisms, potentially influencing pathways involved in the pathophysiology of cerebral vasculopathy. Here, we evaluated the association between VDR gene polymorphisms and 25-hydroxyvitamin D (25(OH)D) levels with CVD in a cohort of patients with SCA. The frequency of CVD and laboratory data were retrospectively obtained from the medical records. Genotyping for the functional FokI (rs2228570) and Cdx-2 (rs11568820) VDR polymorphisms was performed in 459 unrelated SCA patients. 25(OH)D levels were measured in a subset of 45 patients. The TT genotype of the FokI VDR polymorphism was associated with a higher frequency (OR: 2.82; 95% CI: 1.38-5.76, p = 0.006) and higher cumulative incidence (34% vs 16%, p = 0.001) of CVD compared to the other genotypes. Among patients under hydroxyurea (HU) therapy, individuals with the TT-FokI genotype (median: 13.9 ng/mL) had lower 25(OH)D levels compared to those with CC/CT genotypes (median: 20.2 ng/mL; p = 0.033). Similarly, patients with CVD and the TT-FokI genotype (median: 12.3 ng/mL) had reduced 25(OH)D levels compared to CC/CT carriers (median: 20.8 ng/mL; p = 0.034). These findings suggest that the FokI VDR polymorphism may serve as a potential genetic modulator of cerebrovascular complications in individuals with SCA.

Metabolic reprogramming is a hallmark of cancer, with acute myeloid leukemia (AML) being no exception. Mitochondrial function, particularly its role in protecting tumor cells against chemotherapy, is of significant interest in AML chemoresistance. In this study, we identified mitochondrial DNA content (mtDNAc), measured by quantitative PCR, as a simple and precise marker to stratify the metabolic states of AML patients. We show that patients with high mtDNAc are associated with increased mitochondrial metabolism and a higher dependency on oxidative phosphorylation (OXPHOS), often correlating with chemoresistance. Clinically, patients receiving cytarabine and an anthracycline-based regimen (7 + 3 regimen) experienced inferior relapse-free survival and a higher overall rate of leukemia recurrence. Ex vivo experiments using primary AML samples confirmed cytarabine resistance in high mtDNAc patients, which could be overcome by inhibiting mitochondrial complex I. The FDA-approved drug metformin, which targets mitochondrial metabolism, significantly enhanced apoptosis in response to chemotherapy or targeted agents, such as venetoclax, in AML models. However, metformin-treated cells adapted by increasing glycolysis and NAD⁺ production, a resistance mechanism that could be bypassed by targeting the nicotinamide phosphoribosyltransferase (NAMPT) enzyme. In summary, we demonstrated that mtDNAc is an effective tool for assessing the metabolic state of AML cells. This method can be easily implemented in clinical practice to identify chemoresistant patients and guide personalized treatment strategies, including novel combination therapies for those with a high reliance on mitochondrial metabolism.

Summary: The occurrence and severity of osteonecrosis in sickle cell anaemia (SCA) vary due to risk factors, including genetic modifiers. Bone morphogenetic proteins (BMPs), particularly BMP6, and the vitamin D receptor (VDR) play key roles in cartilage and bone metabolism, making them potential contributors to orthopaedic outcomes in SCA. Here, we evaluated the association of polymorphisms in BMP6 (rs3812163, rs270393 and rs449853) and VDR (FokI rs2228570 and Cdx2 rs11568820) genes with osteonecrosis risk in a Brazilian SCA cohort. A total of 177 unrelated SCA patients were selected. The AA genotype of BMP6 rs3812163 was independently associated with a lower osteonecrosis risk (p = 0.015; odds ratio (OR): 0.38; 95% confidence interval (CI): 0.18–0.83) and with the long‐term cumulative incidence of osteonecrosis (p = 0.029; hazard ratio: 0.56, 95% CI: 0.34–0.94). The VDR rs2228570 TT genotype was independently associated with a lower osteonecrosis risk (p = 0.039; OR: 0.14; 95% CI: 0.02–0.90). In summary, our results provide evidence that BMP6 rs3812163 and the VDR rs2228570 might be implicated in osteonecrosis pathophysiology in SCA and might help identify individuals at high risk.

It is increasingly becoming clear that cancers are a symbiosis of diverse cell types and tumor clones. Combined single-cell RNA sequencing, flow cytometry, and immunohistochemistry studies of the innate immune compartment in the bone marrow of patients with acute myeloid leukemia (AML) reveal a shift toward a tumor-supportive M2-polarized macrophage landscape with an altered transcriptional program, with enhanced fatty acid oxidation and NAD ⁺ generation. Functionally, these AML-associated macrophages display decreased phagocytic activity and intra–bone marrow coinjection of M2 macrophages together with leukemic blasts strongly enhances in vivo transformation potential. A 2-day in vitro exposure to M2 macrophages results in the accumulation of CALR ^low leukemic blast cells, which are now protected against phagocytosis. Moreover, M2-exposed “trained” leukemic blasts display increased mitochondrial metabolism, in part mediated via mitochondrial transfer. Our study provides insight into the mechanisms by which the immune landscape contributes to aggressive leukemia development and provides alternatives for targeting strategies aimed at the tumor microenvironment.