Hypertension and kidney disease: a deadly connection

Improving microvascular outcomes in patients with diabetes through management of hypertension

Diabetes mellitus is an independent risk factor for cardiovascular disease (CVD) and current opinion holds that hyperglycemia directly damages smaller blood vessels, resulting in microvascular complications of nephropathy, retinopathy, and neuropathy. In a patient with diabetes, hypertension compounds and greatly increases the risk of microvascular complications, and thus the risk of end-stage kidney disease, vision loss, and nontraumatic limb amputations. Hypertension and hyperglycemia directly damage the microvasculature, leading to small vessel dysfunction that manifests as the clinical disease states of diabetic retinopathy and nephropathy. Early recognition and treatment of both hyperglycemia and hypertension may prevent vision loss and chronic kidney disease, the devastating outcomes of these microvascular complications. One of the pathogenic mechanisms for microvascular dysfunction is upregulation of the angiotensin II type 1 receptor, the most physiologically common receptor for the vasoconstrictor properties of angiotensin II. In patients with diabetic retinopathy and nephropathy, tight control of blood pressure (BP) (< 130/80 mm Hg) delays the progression of retinopathy and nephropathy in addition to reducing cardiovascular morbidity and mortality. Aggressive treatment with 2 or more antihypertensive agents, selected from different drug classes, is often needed to reach the optimal BP target level. A PubMed search was conducted to identify randomized controlled trials that evaluated hypertension control and microvascular outcomes in patients with diabetes. Several clinical trials have yielded promising data with renin-angiotensin-aldosterone system (RAAS) inhibitors (the direct renin inhibitor aliskiren, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers). Attainment of BP control with RAAS inhibitors reduces the risk for CVD, nephropathy, and retinopathy. In addition, RAAS inhibitors have demonstrated renoprotective effectiveness independent of the BP reduction achieved. This review will examine the results of clinical trials in the context of BP control, diabetes, and the microvascular complications of retinopathy and nephropathy.

Association of candidate gene polymorphisms with chronic kidney disease in Japanese individuals with hypertension

Although hypertension has been recognized as a risk factor for chronic kidney disease (CKD), the genetic factors for predisposition to CKD in individuals with hypertension remain largely unknown. The purpose of this study was to identify the genetic variants that confer susceptibility to CKD among individuals with hypertension. The study population comprised 3696 Japanese individuals with hypertension (2265 men, 1431 women), including 1257 individuals (789 men, 468 women) with CKD (estimated glomerular filtration rate (eGFR) <60 ml min(-1) per 1.73 m(2)) and 2439 controls (1476 men, 963 women; eGFR >or=60 ml min(-1) per 1.73 m(2)). The genotypes for 30 polymorphisms of 26 candidate genes were determined. An initial screening of allele frequencies by the chi(2)-test revealed that eight polymorphisms were significantly (false discovery rate <0.05) associated with the prevalence of CKD in hypertensive individuals. Subsequent multivariable logistic regression analysis with adjustment for covariates as well as a stepwise forward selection procedure revealed that the T --> C (Val591Ala) polymorphism of APOB (rs679899), the -681C --> G polymorphism of PPARG (rs10865710), the T --> C (Cys1367Arg) polymorphism of WRN (rs1346044), the -850C --> T polymorphism of TNF (rs1799724), the -219G --> T polymorphism of APOE (rs405509), the C --> T polymorphism of PTGS1 (rs883484) and the 41A --> G (Glu14Gly) polymorphism of ACAT2 (rs9658625) were significantly (P<0.05) associated with the prevalence of CKD. Our results suggest that APOB, WRN, ACAT2, APOE, PPARG, TNF and PTGS1 are susceptibility loci for CKD among Japanese individuals with hypertension. Determination of the genotypes for these polymorphisms may prove informative for the assessment of genetic risk for CKD among such individuals.