Identification of inflammatory biomarkers for pediatric malarial anemia severity using novel statistical methods.

Areas where Plasmodium falciparum transmission is holoendemic are characterized by high rates of pediatric severe malarial anemia (SMA) and associated mortality. Although the etiology of SMA is complex and multifactorial, perturbations in inflammatory mediator production play an important role in the pathogenic process. As such, the current study focused on identification of inflammatory biomarkers in children with malarial anemia. Febrile children (3 to 30 months of age) presenting at Siaya District Hospital in western Kenya underwent a complete clinical and hematological evaluation. Children with falciparum malaria and no additional identifiable anemia-promoting coinfections were stratified into three groups: uncomplicated malaria (hemoglobin [Hb] levels of ≥11.0 g/dl; n = 31), non-SMA (Hb levels of 6.0 to 10.9 g/dl; n = 37), and SMA (Hb levels of <6.0 g/dl; n = 80). A Luminex hu25-plex array was used to determine potential biomarkers (i.e., interleukin 1β [IL-1β], IL-1 receptor antagonist [IL-1Ra], IL-2, IL-2R, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, IL-15, IL-17, tumor necrosis factor alpha [TNF-α], alpha interferon [IFN-α], IFN-γ, granulocyte-macrophage colony-stimulating factor [GM-CSF], macrophage inflammatory protein 1 alpha [MIP-1α], MIP-1β, IFN-inducible protein of 10 kDa [IP-10], monokine induced by IFN-γ [MIG], eotaxin, RANTES, and monocyte chemoattractant protein 1 [MCP-1]) in samples obtained prior to any treatment interventions. To determine the strongest biomarkers of anemia, a parsimonious set of predictor variables for Hb was generated by least-angle regression (LAR) analysis, controlling for the confounding effects of age, gender, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and sickle cell trait, followed by multiple linear regression analyses. IL-12p70 and IFN-γ emerged as positive predictors of Hb, while IL-2R, IL-13, and eotaxin were negatively associated with Hb. The results presented here demonstrate that the IL-12p70/IFN-γ pathway represents a set of biomarkers that predicts elevated Hb levels in children with falciparum malaria, while activation of the IL-13/eotaxin pathway favors more profound anemia.