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Plasma Proteomic Profile of Osteonecrosis in Sickle Cell Anemia Patients and the Influence of Hydroxyurea Therapy

Year: 2026

Type: article

Abstract: Introduction Sickle cell anemia (SCA) is a monogenic disease caused by a mutation in the beta globin gene that ultimately leads to the sickling of erythrocytes. This alteration predisposes to vaso-occlusive and hemolytic events that cause several clinical manifestations, including osteonecrosis (ON), one of the most common complications in SCA. The molecular mechanisms involved in the pathophysiology of ON remain poorly understood. Most patients with SCA are treated with hydroxyurea (HU), however, questions remain regarding its benefits and role in preventing ON. In this context, proteomic analysis may contribute to provide insights into the pathophysiology of ON in SCA, as well as the impact of HU therapy. Objectives To evaluate the plasma proteomic profile of SCA patients with and without ON and the influence of HU on this profile. Methods Plasma samples from 40 adult SCA patients followed at the Hemotherapy Foundation of Pernambuco (HEMOPE) were stratified into four groups according to ON status and HU treatment. The groups consisted of SCA individuals with and without ON, subdivided into those who had been using HU for at least six months and those who were not using it. Samples from each group were pooled, resulting in four pools that were subsequently subjected to analysis. Prior to proteomic analysis, plasma samples underwent albumin and IgG depletion, quantification, clean-up, and enzymatic digestion using trypsin. Analysis was performed using high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in triplicates of the four experimental pools. DAPs were identified and functional enrichment analyses were performed using Progenesis QI, OmicScope, and RStudio, with UniProt and GeneOntology as databases. Results A total of 137 differentially accumulated proteins (DAPs) were quantified across the four experimental groups. Comparative analysis indicated that the groups exhibited significantly distinct proteomic profiles. In individuals with ON, DAP evaluation revealed an increase in proteins associated with complement system hyperactivation and related to a hypercoagulable state, characterized by elevated levels of proteins with prothrombotic functions, including prothrombin, and complement components. Conversely, a decrease in plasminogen and vitamin K-dependent protein S was demonstrated, reflecting impaired thrombotic control and compromised tissue remodeling processes in ON-affected areas. Regarding HU therapy, data indicate that its use influences the regulation of antioxidant and inflammatory pathways, as evidenced by increased hemopexin levels. However, HU therapy did not affect the levels of proteins essential for angiogenesis, cell anchorage, and the restoration of damaged bone structure, such as Insulin-like growth factor-binding protein complex acid labile subunit (IGFALS) and Fibronectin (FN1). Conclusion This study proposes potential molecular mechanisms involved in the pathophysiology of ON in SCA and their relationship with HU treatment. The evidence demonstrates that ON may be associated with an imbalance between coagulation regulation and immune system activation. These mechanisms should be confirmed in future studies through the validation of proteomic data using complementary techniques.

Source: Hematology Transfusion and Cell Therapy

DOI: 10.1016/j.htct.2026.106692