Blood plasma metabolomics of children and adolescents with sickle cell anaemia treated with hydroxycarbamide: a new tool for uncovering biochemical alterations.

Sickle cell anaemia (SCA) is a debilitating genetic haemoglobinopathy predominantly affecting the disenfranchised strata of society in Africa and the Americas. The most common pharmacological treatment for this disease is the administration of hydroxycarbamide (HC) for which questions remain regarding its mechanism of action, efficacy and long-term toxicity specifically in paediatric individuals. A multiplatform metabolomics approach was used to assess the metabolome of plasma samples from a population of children and adolescents with SCA with and without HC treatment along with non-SCA individuals. Fifty-three metabolites were identified by ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) and 1 H nuclear magnetic resonance (NMR) with a predominance of membrane lipids, amino acids and organic acids. The partial least-squares discriminant analysis (PLS-DA) analysis allowed a clear discrimination between the different studied groups, revealing clear effects of the HC treatment in the patients' metabolome including rescue of specific metabolites to control levels. Increased creatine/creatinine levels under HC treatment suggests a possible increase in the arginine pool and increased NO synthesis, supporting existing models for HC action in SCA. The metabolomics results extend the current knowledge on the models for SCA pathophysiology including impairment of Lands' cycle and increased synthesis of sphingosine 1-phosphate. Putative novel biomarkers are suggested.

Blood plasma and bone marrow interstitial fluid metabolomics of sickle cell disease patients with osteonecrosis: An exploratory study to dissect biochemical alterations.

Individuals with sickle cell disease (SCD) often experience numerous vaso-occlusive crisis events throughout their lives, which can progress to severe damage of several organs, including avascular necrosis, also known as osteonecrosis (ON). Osteonecrosis is one of the most devastating musculoskeletal clinical manifestations of sickle cell disease, afflicting up to 50% of the SCD patients. Herein, a NMR-based untargeted metabolomics approach was used to assess the metabolome alterations of blood plasma and bone marrow interstitial fluid (BMIF) samples of SCD patients with osteonecrosis. Furthermore, biochemical signatures associated with different osteonecrosis stages were assessed by analysing the metabolome of blood plasma and bone marrow interstitial fluid samples of SCD patients with different stages of the disease based on the Fiat and Arlet classification (FAC). Multivariate statistical analysis allowed a clear discrimination between the studied groups and it provided important insights into the different osteonecrosis stages. Citrate was pointed out as a possible biomarker to differentiate SCD patients with and without osteonecrosis. Acetate, creatinine, histidine, tyrosine, glucose, and NI5 seems to be key metabolites associated to different stages of the disease. Although this is a pioneer exploratory study, we acknowledge that fact that it is limited by the group sizes and absence of a validation cohort. Nevertheless, multivariate statistical analyses indicated that the metabolome of blood plasma and BMIF samples encompasses a complex metabolic regulation system for osteonecrosis.

1H NMR-based metabolite profiling for biomarker identification.

The metabolome is affected by individual physiologic and pathophysiologic states as well as the environment. Metabolomics has become crucial approach for clinical studies, providing a better understanding of disease mechanisms. The expansion of analytical methods aiming at performing detailed analysis of biofluids has led to the characterization of many disease biomarkers. NMR provides faster and more comprehensive assessment of the biological samples in human models. NMR-based profiling studies aimed at identifying biomarkers for specific diseases has significantly increased over the last few years. These have attempted to correlate human pathophysiology with alterations in the metabolic profile of common biofluids such as urine, plasma and serum. In this context, NMR-based untargeted metabolomics has become an important adjunct for the identification of biomarkers in disease research, not only for early diagnosis purposes, but also for therapy prediction, precise prognosis or monitoring of disease progression. This review critically discusses recent findings of urine (non-invasive) and blood serum and plasma (minimally invasive) metabolomics, focusing on key role of metabolites and their use as potential biomarkers for diagnostic purposes.