Bone morphogenic protein-7 serum level decreases significantly in patients with contrast-induced nephropathy

Imbalance in Bone Morphogenic Proteins 2 and 7 Is Associated with Renal and Cardiovascular Damage in Chronic Kidney Disease

Arterial stiffness is a major vascular complication of chronic kidney disease (CKD). The development of renal damage, hypertension, and increased pulse wave velocity (PWV) in CKD might be associated with an imbalance in bone morphogenetic proteins (BMP)-2 and BMP-7. Plasma BMP-2 and BMP-7 were determined by ELISA in CKD patients (stages I-III; n = 95) and Munich Wistar Frömter (MWF) rats. Age-matched Wistar rats were used as a control. The expression of BMP-2, BMP-7, and profibrotic and calcification factors was determined in kidney and perivascular adipose tissues (PVAT). BMP-2 was higher in stage III CKD patients compared to control subjects. BMP-7 was lower at any CKD stage compared to controls, with a significant further reduction in stage III patients. A similar imbalance was observed in MWF rats together with the increase in systolic (SBP) and diastolic blood pressure (DBP), or pulse wave velocity (PWV). MWF exhibited elevated urinary albumin excretion (UAE) and renal expression of BMP-2 or kidney damage markers, Kim-1 and Ngal, whereas renal BMP-7 was significantly lower than in Wistar rats. SBP, DBP, PWV, UAE, and plasma creatinine positively correlated with the plasma BMP-2/BMP-7 ratio. Periaortic and mesenteric PVAT from MWF rats showed an increased expression of BMP-2 and profibrotic and calcification markers compared to Wistar rats, together with a reduced BMP-7 expression. BMP-2 and BMP-7 imbalance in plasma, kidney, and PVATs is associated with vascular damage, suggesting a profibrotic/pro-calcifying propensity associated with progressive CKD. Thus, their combined analysis stratified by CKD stages might be of clinical interest to provide information about the degree of renal and vascular damage in CKD.

BMP-7 Signaling and its Critical Roles in Kidney Development, the Responses to Renal Injury, and Chronic Kidney Disease

Chronic kidney disease (CKD) is a significant health problem that most commonly results from congenital abnormalities in children and chronic renal injury in adults. The therapeutic potential of BMP-7 was first recognized nearly two decades ago with studies demonstrating its requirement for kidney development and ability to inhibit the pathogenesis of renal injury in models of CKD. Since this time, our understanding of CKD has advanced considerably and treatment strategies have evolved with the identification of many additional signaling pathways, cell types, and pathologic processes that contribute to disease progression. The purpose of this review is to revisit the seminal studies that initially established the importance of BMP-7, highlight recent advances in BMP-7 research, and then integrate this knowledge with current research paradigms. We will provide an overview of the evolutionarily conserved roles of BMP proteins and the features that allow BMP signaling pathways to function as critical signaling nodes for controlling biological processes, including those related to CKD. We will discuss the multifaceted functions of BMP-7 during kidney development and the potential for alterations in BMP-7 signaling to result in congenital abnormalities and pediatric kidney disease. We will summarize the renal protective effects of recombinant BMP-7 in experimental models of CKD and then propose a model to describe the potential physiological role of endogenous BMP-7 in the innate repair mechanisms of the kidneys that respond to renal injury. Finally, we will highlight emerging clinical approaches for applying our knowledge of BMP-7 toward improving the treatment of patients with CKD.

Biomarkers of Contrast-Induced Nephropathy: Which Ones and What Is Their Clinical Relevance?

Contrast-induced nephropathy, or contrast-induced acute kidney injury (AKI), is an acute impairment of renal function as manifested by an increase in serum creatinine. Different urinary and serum proteins have been intensively investigated as possible biomarkers for the early diagnosis of AKI. Promising candidate biomarkers have the ability to detect an early and graded increase in tubular epithelial cell injury and to distinguish prerenal causes of AKI from acute tubular necrosis. In this article new, emerging biomarkers of contrast-induced AKI are presented and described, of which serum neutrophil gelatinase-associated lipocalin appears to be the most promising.