This review provides insight into the role that obesity, but especially mediators of the adipose tissue, have in both renal disease and transplantation. In particular, we focus on the functions of leptin and adiponectin, inflammatory mediators with widely known clinical implications, as well as on the role of arachidonic acid-derived eicosanoid metabolites. These latter compounds, epoxyeicosatrienoic (EETs) and hydroxyeicosatetraenoic (HETEs) acids, which modulate the liberation of cytokines in the adipose tissue, are generated in the epoxygenase pathway of arachidonic biotransformation via CYP450 enzymes. There is accumulating evidence suggesting that EETs and HETEs may have a critical role in the onset and outcome of chronic kidney disease and renal transplantation. Finally, we also discuss the reported effect that the presence of genetic variants in leptin, adiponectin, EETs and HETEs-related genes may cause in renal patients and recipients. The levels of cytokines of the adipose tissue and related compounds play a remarkable role in both renal disease and transplant. Accordingly, novel therapeutic strategies are being developed based on the modulation of their concentrations in patients with various diseases.

There is a pressing need for more precise biomarkers of chronic kidney disease (CKD). Plasma samples from 820 subjects [231 with CKD, 325 with end-stage kidney disease (ESKD) and 264 controls] were analyzed by LC-MS/MS to determine a metabolic profile of 28 aminoacids (AA) and biogenic amines to test their value as markers of CKD risk and progression. The Kynurenine/Tryptophan ratio showed the strongest correlation with estimated glomerular filtration rate values (coefficient=-0.731, P<0.0001). Models created with Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) containing the metabolic signature showed high goodness of fit and predictability for controls/CKD (R2X:0.73;R2Y:0.92;Q2:0.92) and lower for CDK/ESKD (R2X:0.56;R2Y:0.59;Q2:0.55). Based on generated VIP scores, the most relevant markers for segregating samples into control/CKD or CKD/ESKD groups were citrulline (1.67) and tryptophan (1.59), respectively. ROC analysis showed that the addition of the metabolic profile to a model including CKD classic risk factors improved AUC from 86.7% (83.6-89.9) to 100% (100-100) for CKD risk (P<0.0001), and from 63.0% (58.2-67.8) to 96.5% (95.3-97.8) for the risk of progression from CKD to ESKD (P<0.0001). Plasma concentrations of AA and related amines may be useful as diagnostic biomarkers of kidney disease, both for CKD risk and for progression of CKD patients to ESKD.