Iron Homeostasis And Anemia In Hiv And Tuberculosis
Background: Evidence supports a role for iron homeostasis in the pathogenesis of HIV and tuberculosis. The iron regulatory peptide, hepcidin, inhibits both dietary iron absorption and iron efflux leading to macrophage iron retention. Conditions associated with elevated hepcidin, which include altered concentrations of ferritin, transferrin and hemoglobin, may favor Mycobacterium tuberculosis iron acquisition, HIV progression and anemia. In light of this, we investigated iron homeostasis biomarkers as risk factors for incident TB and mortality in an HIVseropositive cohort and also for progression to TB in an HIV-seromixed cohort. In addition, we characterized iron homeostasis during TB therapy in order to identify causes of anemia and inform selection of safe, effective and well-timed treatments for anemia. Methods: Clinical and demographic data and archived plasma and serum samples from two research platforms were utilized in this work: the Medical Research Council (MRC) HIV clinical cohort and the MRC TB case contact study. Analysis of iron homeostasis biomarker concentrations was conducted at MRC laboratories in The Gambia. Results: During HIV Clinical Cohort follow up, 32 incident tuberculosis cases were identified and 64% of the 196 participants died. Greater hepcidin was associated with significantly increased likelihood of tuberculosis and greater all-cause mortality. This was consistent with observed higher ferritin and hepcidin concentrations in HIV-seromixed contacts of infectious TB cases that progressed to TB earlier. Analysis of biomarkers and anemia during TB therapy revealed that anemia of inflammation was predominant TB diagnosis, declining significantly after six months of treatment; however, a corresponding reduction was not evident for anemia with iron-responsive components. Hepcidin concentrations significantly declined after 2 months of TB treatment. Conclusions: Changes in iron homeostasis biomarkers are associated with incident TB and mortality in HIV and progression to TB disease among contacts of infectious TB cases. Further studies are needed to elucidate mechanisms and determine the clinical utility of monitoring iron homeostasis biomarkers. TB therapy is associated with significant reductions in anemia of inflammation, but iron-based interventions are needed for anemia with iron responsive components. Monitoring hepcidin reveals a window for intervention opening as early as two months into TB treatment.
Hepcidin, Ferritin, Transferrin,; Inflammation, Africa
Gu,Zhenglong; Rudd,Brian D; McCormick,Charles Chipley W
Ph. D., Nutrition
Doctor of Philosophy
dissertation or thesis