Relationships of Thickness of Perirenal Fat with Urinary Levels of MCP-1 and NGAL in Patients with Hypertension.

Abstract

We conducted a study to determine the relationships between perirenal fat (PRF) thickness and urinary levels of monocyte chemoattractant protein-1 (MCP-1) and neutrophil gelatinase-associated lipocalin (NGAL) in patients with hypertension (HTN). In 338 HTN patients (aged 63.51±12.3 on average), MCP-1 and NGAL levels were studied using enzyme-linked immunosorbent assay (ELISA). To measure PRF thickness, all patients underwent CT scans. We considered PRF thickness ≥1.91 cm as the diagnostic threshold for perirenal obesity. Patients with excessive PRF thickness exhibited significantly lower levels of MCP-1 and NGAL compared with those with PRF thickness ≥1.91 cm: 0.98 pg/mL (interquartile range, 0.21 to 2.05) vs. 2.35 pg/mL (0.37 to 5.22) for MCP-1 and 50.0 pg/mL (48.9 to 67.8) vs. 98.3 pg/mL (68.4 to 187.1) for NGAL. We found a relationship of PRF thickness with both MCP-1 (r=0.46, P<0.05) and NGAL (r=0.53, P<0.05), the levels of which were significantly different in patients with first- and third-stage chronic kidney disease: 0.33 pg/mL (0.21 to 1.35) vs. 4.47 pg/mL (0.23 to 10.81); 50.0 pg/mL (49.4 to 85.5) vs. 126.45 pg/mL (57.5 to 205.15), respectively (P=0.04). Patients with metabolically healthy obesity (MHO) had significantly lower MCP-1 levels than those with metabolically unhealthy obesity (MUHO): 0.65 pg/mL (0.21 to 2.15) vs. 3.28 pg/mL (2.05 to 5.22) (P=0.014). MHO patients showed significantly lower NGAL levels than MUHO patients: 50.0 pg/mL (49.4 to 62.2) vs. 98.3 pg/mL (50.0 to 174.8) (P=0.04). Multiple linear regression analysis revealed significant relationships of MCP-1 with PRF thickness (β±standard error, 0.41±0.15; P<0.001) and smoking (0.26±0.13; P=0.01) and of NGAL with age (0.45±0.16; P<0.01) and PRF thickness (0.49±0.15; P<0.001). We identified higher concentrations of renal fibrosis markers in patients with perirenal and metabolically unhealthy obesity as well as a link between PRF thickness and MCP-1 and NGAL levels in urine.