Background: Lipocalin-2/neutrophil gelatinase-B associated lipocalin (Lcn2/NGAL) is involved in the transport of iron and seems to play an important role in inflammation. A recent study has reported that it is also expressed in the failing heart and may be a biomarker not only for renal failure but also for heart failure. Because Lcn2/NGAL is thought to be induced by interleukin-1, it might be strongly induced in the presence of myocarditis.
Methods and results: This study investigated the expression of Lcn2/NGAL in rat experimental autoimmune myocarditis (EAM) and in human myocarditis. In EAM hearts, the expression of Lcn2/NGAL was markedly increased (>100-fold at an early stage), and in human myocarditis it was also highly expressed compared with non-inflammatory failing hearts. Lcn2/NGAL expressing cells in hearts with EAM and human myocarditis were identified as cardiomyocytes, vascular wall cells, fibroblasts and neutrophils. Lcn2/NGAL in EAM rats was also expressed in the liver. Plasma Lcn2/NGAL levels abruptly increased at an early stage of EAM, and high levels were initially sustained during the inflammatory stage, then decreased with recovery. In contrast, levels of B-type natriuretic peptide increased only slowly as the disease progressed.
Conclusions: Cardiomyocytes, vascular wall cells and fibroblasts in myocarditis strongly express Lcn2/NGAL via proinflammatory cytokines.