Between 20% and 40% of patients with diabetes ultimately develop diabetic nephropathy, which in the US is the most common cause of end-stage renal disease requiring dialysis. Diabetic nephropathy has several distinct phases of development and multiple mechanisms contribute to the development of the disease and its outcomes. This Review provides a summary of the latest published data dealing with these mechanisms; it focuses not only on candidate genes associated with susceptibility to diabetic nephropathy but also on alterations in various cytokines and their interaction with products of advanced glycation and oxidant stress. Additionally, the interactions between fibrotic and hemodynamic cytokines, such as transforming growth factor beta1 and angiotensin II, respectively, are discussed in the context of new information concerning nephropathy development. We touch on the expanding clinical data regarding markers of nephropathy, such as microalbuminuria, and put them into context; microalbuminuria reflects cardiovascular and not renal risk. If albuminuria levels continue to increase over time then nephropathy is present. Lastly, we look at advances being made to enable identification of genetically predisposed individuals.

The B(1) type receptor of bradykinin (Bk B(1)R) is believed to be physiologically inert but highly inducible by inflammatory mediators and tissue damage. To explore the potential participation of the Bk B(1)R in blood pressure (BP) regulation, we studied mice with deleted Bk B(2)R gene with induced experimental hypertension, either salt-dependent (subtotal nephrectomy with 0.5% NaCl as drinking water) or renin/angiotensin-dependent (renovascular 2-kidney-1-clip). Compared with the wild-type controls, the B(2)R gene knockout mice had a higher baseline BP (109.7+/-1.1 versus 101.1+/-1.3 mm Hg, P:=0.002), developed salt-induced hypertension faster (in 19.3+/-2.3 versus 27.7+/-2.4 days, P:=0.024), and had a more severe end point BP (148+/-3.7 versus 133+/-3.1 mm Hg, P:<0.05). On the contrary, renovascular hypertension developed to the same extent (149.7+/-4.3 versus 148+/-3.6 mm Hg) and in the same time frame (14+/-2.2 versus 14+/-2.1 days). A bolus infusion of a selective B(1)R antagonist at baseline produced a significant hypertensive response (by 11.4+/-2 mm Hg) in the knockout mice only. Injection of graded doses of a selective B(1)R agonist produced a dose-dependent hypotensive response in the knockout mice only. Assessment of tissue expression of B(1)R and B(2)R genes by reverse transcription-polymerase chain reaction techniques revealed significantly higher B(1)R mRNA levels in the B(2)R knockout mice at all times (normotensive baseline and hypertensive end points). At the hypertensive end points, there was always an increase in B(1)R gene expression over the baseline values. This increase was significant in cardiac and renal tissues in all hypertensive wild-type mice but only in the clipped kidney of the renovascular knockout mice. The B(2)R gene expression in the wild-type mice remained unaffected by experimental manipulations. These results confirm the known vasodilatory and natriuretic function of the Bk B(2)R; they also indicate that in its absence, the B(1)R can become upregulated and assume some of the hemodynamic properties of the B(2)R. Furthermore, they indicate that experimental manipulations to produce hypertension also induce upregulation of the B(1)R, but not the B(2)R, in cardiac and renal tissues.

Abstract-The biological actions of bradykinin (BK) are attributed to its B 2 type receptor (B 2 R), whereas the B 1 R is constitutively absent, inducible by inflammation and toxins. Previous studies in B 2 R gene knockout mice showed that the B 1 R is overexpressed, is further upregulated by hypertensive maneuvers, and assumes some of the hemodynamic functions of the B 2 R. The current experiments were designed to further clarify the metabolic function of the B 2 R and to explore whether the upregulated B 1 R can also assume the metabolic function of the missing B 2 R. One group of B 2 RϪ/Ϫ mice (nϭ9) and one of B 2 Rϩ/ϩ controls (nϭ8) were treated for 3 days with captopril (which produced a similar blood pressure-lowering response in both groups) and studied with the hyperinsulinemic euglycemic clamp. The knockout mice had fasting and steady-state blood glucose levels similar to those of the wild-type mice but a had tendency to higher fasting insulin levels (at 27.8Ϯ5.2 versus 18Ϯ2.9 mU/L, respectively). However, they had significantly higher steady-state insulin levels (749Ϯ127. radykinin mediates a variety of biological effects such as vasodilation, vascular permeability, inflammation, pain, and edema. 1 It is also known to play an important role in glucose metabolism. 2,3 Indeed, it was shown in vitro and in vivo that administration of bradykinin increases the glucose uptake in cultured adipocytes 4 as well as in long-term rat experiments 5 and in skeletal muscle of human forearm. 6 ACE inhibitors were shown to improve glucose utilization, 7 an action that is attributed to bradykinin. 8,9 In keeping with these data, kininogen-deficient rats were found to be resistant to insulin. 10 The effects of bradykinin are mediated by the B 1 -or B 2 -type receptor (B 1 R or B 2 R). It has been accepted that almost all of the physiologically significant effects of bradykinin, including the metabolic ones, are exerted by activation of the B 2 R. Indeed, inhibition of the B 2 R by various antagonists was shown to reverse the amelioration of insulindependent glucose transport by ACE inhibitors, 11,12 whereas blockade of downstream mediators, such as prostaglandins and NO, had no effect on insulin sensitivity. 12 Several studies have shown that the B 2 R is expressed in tissues dependent on insulin for glucose uptake, such as skeletal muscle and adipocytes. 4,13,14 On the contrary, the B 1 R is not expressed under normal conditions; it has long been known that its expression is induced by toxins or inflammatory mediators and it contributes to endotoxic shock, 15 but it has not been associated with metabolic functions.In a recent series of studies, investigators have used genetically engineered mice with deleted B 2 R 16 to further explore the physiological actions of bradykinin. Using these mice, we observed that the B 1 R is highly expressed in B 2 R knockout mice and appears to take over some of the hemodynamic properties of the B 2 R. 17 The present experiments were designed to further explore the metabolic function of t...

Exposure of experimental animals to increased angiotensin II (ANG II) induces hypertension associated with cardiac hypertrophy, inflammation, and myocardial necrosis and fibrosis. Some of the most effective antihypertensive treatments are those that antagonize ANG II. We investigated cardiac gene expression in response to acute (24 h) and chronic (14 day) infusion of ANG II in mice; 24-h treatment induces hypertension, and 14-day treatment induces hypertension and extensive cardiac hypertrophy and necrosis. For genes differentially expressed in response to ANG II treatment, we tested for significant regulation of pathways, based on Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Microarray Pathway Profiler (GenMAPP) databases, as well as functional classes based on Gene Ontology (GO) terms. Both acute and chronic ANG II treatments resulted in decreased expression of mitochondrial metabolic genes, notably those for the electron transport chain and Krebs-TCA cycle; chronic ANG II treatment also resulted in decreased expression of genes involved in fatty acid metabolism. In contrast, genes involved in protein translation and ribosomal activity increased expression following both acute and chronic ANG II treatments. Some classes of genes showed differential response between acute and chronic ANG II treatments. Acute treatment increased expression of genes involved in oxidative stress and amino acid metabolism, whereas chronic treatments increased cytoskeletal and extracellular matrix genes, second messenger cascades responsive to ANG II, and amyloidosis genes. Although a functional linkage between Alzheimer disease, hypertension, and high cholesterol has been previously documented in studies of brain tissue, this is the first demonstration of induction of Alzheimer disease pathways by hypertension in heart tissue. This study provides the most comprehensive available survey of gene expression changes in response to acute and chronic ANG II treatment, verifying results from disparate studies, and suggests mechanisms that provide novel insight into the etiology of hypertensive heart disease and possible therapeutic interventions that may help to mitigate its effects.