Searching for novel intercellular signal-transducing molecules in the kidney and their clinical application

Lipocalin (LCN) 2 Mediates Pro-Atherosclerotic Processes and Is Elevated in Patients with Coronary Artery Disease

Background

Lipocalin (LCN) 2 is associated with multiple acute and chronic inflammatory diseases but the underlying molecular and cellular mechanisms remain unclear. Here, we investigated whether LCN2 is released from macrophages and contributes to pro-atherosclerotic processes and whether LCN2 plasma levels are associated with the severity of coronary artery disease progression in humans.

Methods and Results

In an autocrine-paracrine loop, tumor necrosis factor (TNF)-α promoted the release of LCN2 from murine bone-marrow derived macrophages (BMDM) and vice versa. Moreover, LCN2 stimulation of BMDM led to up-regulation of M1 macrophage markers. In addition, enhanced migration of monocytic J774A.1 cells towards LCN2 was observed. Furthermore, LCN2 increased the expression of the scavenger receptors Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) as well as scavenger receptor class A-1 (SRA-1) and induced the conversion of macrophages to foam cells. In atherosclerotic lesions of low density lipoprotein receptor-deficient (ldlr^−/−) mice fed a high fat, high cholesterol diet, LCN2 was found to be co-localized with macrophages in the shoulder region of the atherosclerotic plaque. In addition, LCN2 plasma levels were significantly increased in plasma samples of these mice. Finally, LCN2 plasma levels correlated with the severity of coronary artery disease (CAD) in patients as determined by coronary angiography.

Conclusions

Here we demonstrated that LCN2 plays a pivotal role in processes involved in atherogenesis by promoting polarization and migration of monocytic cells and development of macrophages towards foam cells. Moreover, LCN2 may be used as a prognostic marker to determine the status of CAD progression.

Urine neutrophil gelatinase associated lipocalin as an early marker of acute kidney injury in hematopoietic stem cell transplantation patients

Acute kidney injury (AKI) is common in hematopoietic stem cell transplantation (HSCT) patients with an incidence of 21-73%. Prevention and early diagnosis reduces the frequency and severity of this complication. Predictive biomarkers are of major importance to timely diagnosis. Neutrophil gelatinase associated lipocalin (NGAL) is a widely investigated novel biomarker for early diagnosis of AKI. However, no study assessed NGAL for AKI diagnosis in HSCT patients. We performed further analyses on gathered data from our recent trial to evaluate the performance of urine NGAL (uNGAL) as an indicator of AKI in 72 allogeneic HSCT patients. AKI diagnosis and severity were assessed using Risk-Injury-Failure-Loss-End-stage renal disease and AKI Network criteria. We assessed uNGAL on days -6, -3, +3, +9 and +15. Time-dependent Cox regression analysis revealed a statistically significant relationship between uNGAL and AKI occurrence. (HR = 1.04 (1.008-1.07), p = 0.01). There was a relation between uNGAL day + 9 to baseline ratio and incidence of AKI (unadjusted HR = 1.047 (1.012-1.083), p < 0.01). The area under the receiver-operating characteristic curve for day + 9 to baseline ratio was 0.86 (0.74-0.99, p < 0.01) and a cut-off value of 2.62 was 85% sensitive and 83% specific in predicting AKI. Our results indicated that increase in uNGAL augmented the risk of AKI and the changes of day +9 uNGAL concentrations from baseline could be of value for predicting AKI in HSCT patients. Additionally uNGAL changes preceded serum Cr raises by nearly 2 days.