Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Kidney Injury Molecule 1 (KIM1) in patients with diabetic nephropathy: a cross-sectional study and the effects of lisinopril.

AIMS: Our aim was to evaluate the markers of tubulointerstitial damage, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule1 (KIM1) in Type 1 diabetic patients with different levels of albuminuria and in control subjects. In addition, the effect of renoprotective treatment on urinary NGAL was evaluated in diabetic nephropathy. METHODS: This was a cross-sectional study in 58 normoalbuminuric (u-albumin <30 mg/24 h), 45 microalbuminuric (30-300 mg/24 h) and 45 macroalbuminuric (>300 mg/24 h) Type 1 diabetic patients and 55 non-diabetic control subjects. Furthermore, in a second study, urine-NGAL was measured in a randomized cross-over study of 56 Type 1 diabetic patients with diabetic nephropathy treated with lisinopril 20, 40 and 60 mg daily. RESULTS: Urine-NGAL levels were [geometric mean (95% CI)]: control subjects 74 (52-104) (pg/mmol creatinine), normoalbuminuric 146 (97-221), microalbuminuric 222 (158-312) and macroalbuminuric group 261 (175-390). Urine-NGAL increased significantly from the normo- to the micro- and further to the macroalbuminuric group (P<0.05). Urine-NGAL was higher in normoalbuminuric vs. control subjects (P<0.01). Plasma-NGAL was significantly higher in the normoalbuminuric and macroalbuminuric groups than in the control group. Urine-KIM1 was higher in all diabetic groups than in the control group (P<0.001), with no difference between diabetic groups. During lisinopril treatment, urine-NGAL was reduced (95% CI) 17% (11-50) (not significant). CONCLUSIONS: Urine-NGAL and urine-KIM1 (u-KIM1) are elevated in Type1 diabetic patients, with or without albuminuria, indicating tubular damage at an early stage. Urine-NGAL increases significantly with increasing albuminuria. The ACE inhibitor lisinopril reduced urine-NGAL, but this was not statistically significant.

Optimal dose of lisinopril for renoprotection in type 1 diabetic patients with diabetic nephropathy: a randomised crossover trial.

AIMS/HYPOTHESIS: The purpose of this study was to evaluate the optimal renoprotective effect of ultrahigh doses of lisinopril, as reflected by short-term changes in urinary albumin excretion rate (UAER), in type 1 diabetic patients with diabetic nephropathy. METHODS: At the Steno Diabetes Center, 49 type 1 diabetic patients with diabetic nephropathy completed this double-masked randomised crossover trial consisting of an initial washout period followed by three treatment periods each lasting 2 months, where all patients received lisinopril 20, 40 and 60 mg once daily in randomised order in addition to slow-release furosemide. Allocation was concealed by sequentially numbered opaque sealed envelopes. UAER, 24 h ambulatory blood pressure (ABP) and estimated GFR were determined at baseline and after each treatment period. RESULTS: All 49 patients completed all three treatment periods. Baseline values were: UAER (geometric mean [95% CI]) 362 (240-545) mg/24 h, 24 h ABP (mean [SD]) 142 (14)/74 (8) mmHg and estimated GFR 75 (29) ml min(-1) 1.73 m(-2). Reductions in UAER from baseline were 63%, 71% and 70%, respectively, with the increasing doses of lisinopril (p < 0.001). Compared with lisinopril 20 mg there was a further reduction in UAER of 23% with lisinopril 40 mg and 19% with 60 mg, p < 0.05. ABP was reduced from baseline by 10/5, 13/7 and 12/7 mmHg (p < 0.001 vs baseline, p < 0.05 for diastolic ABP 20 vs 40 mg, otherwise NS between doses). The difference in UAER between 20 and 40 mg lisinopril was significant after adjustment for changes in ABP (p < 0.01). Two patients were excluded from the study because of an increase in plasma creatinine and one because of high BP; otherwise the study medication was well tolerated with few, mild, dose-independent adverse effects. CONCLUSIONS/INTERPRETATION: Lisinopril 40 mg once daily is generally safe and offers additional reductions in BP and UAER in comparison with the currently recommended dose of 20 mg. Lisinopril 60 mg offers no further beneficial effect. TRIAL REGISTRATION: ClinicalTrials.gov NCT00118976.

Long-term prevention of diabetic nephropathy: an audit.

AIMS/HYPOTHESIS: In type 1 diabetic patients with microalbuminuria not receiving antihypertensive treatment, an increase in urinary AER (UAER) of 6-14%/year and a risk of developing diabetic nephropathy (DN) of 3-30%/year have been reported. We audited the long-term effect of blocking the renin-angiotensin-aldosterone system (RAAS) with an ACE inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in microalbuminuric type 1 diabetic patients on progression of microalbuminuria and development of DN. METHODS: All patients with type 1 diabetes and persistent microalbuminuria (30-300 mg/24 h) were identified (n=227) in 1995 at Steno Diabetes Center and followed for 11 years. Development of DN was defined as a UAER of >300 mg/24 h in two of three consecutive urine samples. RESULTS: Age and duration of diabetes at baseline (mean+/-SD) were 46+/-15 and 28+/-13 years, respectively. During follow-up 14 patients emigrated and 58 (26%) died. Over the same period 79% were treated with an ACEI or ARB. There was a mean decline in UAER of 4%/year. Sixty-five patients (29%) progressed to overt DN, corresponding to 3.1%/year. However, 29 of them regressed to normo- or microalbuminuria on intensified antihypertensive treatment. Glycaemic control and blood pressure remained nearly unchanged. CONCLUSIONS/INTERPRETATION: In our outpatient clinic, the implementation of RAAS-blocking treatment in type 1 diabetic patients with microalbuminuria successfully reduced long-term progression to overt DN to a rate similar to those previously reported in randomised, double-blind intervention trials of shorter duration using RAAS blockade.

Time course of the antiproteinuric and antihypertensive effects of direct renin inhibition in type 2 diabetes.

Inhibition of renin with an active site inhibitor, aliskiren, lowers blood pressure (BP) in diabetic patients. Here, we studied the time course of the antihypertensive and antiproteinuric effect of renin inhibition in 15 patients with type 2 diabetes and elevated urinary albumin/creatinine ratios (UACRs) to check whether aliskiren can decrease proteinuria. After a 4-week washout of previous medications, patients received aliskiren and furosemide daily for 28 days followed by a 4-week withdrawal period. Twenty-four-hour BPs were measured at baseline throughout treatment and withdrawal periods. The UACR was significantly reduced after 2-4 days of treatment with another significant reduction after 28 days. Systolic blood pressure (SBP) was significantly lower after 7 days with no further reduction after 28 days. The BP returned toward baseline 3 days after withdrawal, whereas the UACR was still significantly reduced compared with baseline 12 days after withdrawal. Our study shows that aliskiren reduced 24 h SBP, and this was associated with a reduction in albuminuria in type 2 diabetic patients.

Beneficial impact of spironolactone on nephrotic range albuminuria in diabetic nephropathy.

Reduction of nephrotic range albuminuria is associated with markedly improved renal and cardiovascular outcome in patients with diabetic nephropathy. Aldosterone has been suggested to play a role in the progression of diabetic nephropathy. We therefore aimed to evaluate the short-term effect of aldosterone antagonism with spironolactone on nephrotic range albuminuria and blood pressure in diabetic nephropathy. Twenty Caucasian patients with diabetic nephropathy and nephrotic range albuminuria (>2500 mg/24 h) despite recommended antihypertensive treatment completed this double-masked, randomized crossover trial. Patients were treated in random order with spironolactone 25 mg once daily and matched placebo for 2 months, on top of ongoing antihypertensive treatment, including an angiotensin-converting enzyme inhibitor or an angiotensin II receptor blocker in maximally recommended doses. Median (range) number of antihypertensive drugs was 3 (2-5). After each treatment period, albuminuria, 24-h ambulatory blood pressure, and glomerular filtration rate (GFR) were determined. Spironolactone on top of recommended renoprotective treatment induced a 32% (95% confidence interval (CI): 21-42%) reduction in albuminuria from (geometric mean (95% CI)) 3718 (2910-4749) mg/24 h on placebo treatment (P<0.001). There was a significant reduction in 24-h blood pressure of 6 (2-10)/4 (2-6) mm Hg and day blood pressure of 7 (3-12)/5 (3-7) mm Hg (P<0.01), whereas night blood pressure remained unchanged. Spironolactone induced an insignificant reversible reduction in GFR of 3 ml/min/1.73 m2 from 64 (27) ml/min/1.73 m2. No patients were excluded due to adverse events. Our results suggest that spironolactone treatment on top of recommended renoprotective treatment including maximal renin-angiotensin system blockade may offer additional renoprotection in patients with diabetic nephropathy and nephrotic range albuminuria.

Aldosterone synthase (CYP11B2) -344T/C polymorphism is not associated with the initiation and progression of diabetic nephropathy in Caucasian Type 1 diabetic patients.

AIMS: Aldosterone is one of the main effectors of the renin-angiotensin-aldosterone system regulating blood pressure. Previous studies have shown that the aldosterone synthase promoter polymorphism -344T/C influences aldosterone levels and is associated with hypertension, a risk factor for the initiation and progression of diabetic nephropathy. Therefore, we investigated whether the -344T/C polymorphism is associated with the development and progression of diabetic nephropathy in Type 1 diabetes mellitus. METHODS: The -344T/C polymorphism was determined using standard PCR techniques in 422 Type 1 diabetic patients with overt diabetic nephropathy [mean age 43 years (SD 11)], and in 479 patients with persistent normoalbuminuria and long-standing Type 1 diabetes [age 47 years (SD 12), duration of diabetes 27 years (SD 10)]. Furthermore, we genotyped 163 Type 1 diabetic patients with overt diabetic nephropathy treated with angiotensis-converting enzyme inhibitors (ACE-I). These patients were followed for a median of 6 years (range 3-14), with nine measurements (range 3-29) of glomerular filtration rate (GFR), and had a decline in GFR of 3.1 (-3.2; 23.7) ml/min per year. RESULTS: There was no significant difference between cases and controls in either genotype distributions (cases TT 0.33, TC 0.48, CC 0.19; controls TT 0.32, TC 0.48, CC 0.20) or allele frequencies (cases T/C 0.57/0.43; controls T/C 0.56/0.44). Furthermore, a genotype-phenotype interaction analysis in the normoalbuminuric patients revealed no differences in sex distribution, age, duration of diabetes, blood pressure, HbA(1c,) or urinary albumin excretion rate across genotypes. In the observational follow-up study, the rate of decline in GFR did not differ between groups of patients with different -344T/C genotype (P = 0.41). However, the T-allele made a statistically significant contribution to both systolic and diastolic pressure during follow-up (P = 0.006 and 0.032, respectively). CONCLUSIONS: The -344T/C polymorphism of the aldosterone synthase gene is not associated with initiation or progression of diabetic nephropathy in Caucasian Type 1 diabetic patients, but modulates blood pressure variation.

Aldosterone synthase (CYP11B2)-344T/C polymorphism and renoprotective response to losartan treatment in diabetic nephropathy.

OBJECTIVE: It has been suggested that an aldosterone synthase gene polymorphism (CYP11B2 -344T/C) is predictive of the blood pressure lowering effect of angiotensin II receptor blockers in essential hypertension. We investigated whether this polymorphism is predictive of reductions in blood pressure and albuminuria and preservation of glomerular filtration rate (GFR) during short-term and long-term treatment with losartan in 57 hypertensive type-1 diabetic patients with diabetic nephropathy. MATERIAL AND METHODS: After a 4-week washout period, patients received losartan (100 mg o.d.) and were followed for a mean follow-up of 36 months. At baseline, after 2 and 4 months, and every 6 months thereafter, GFR (51Cr-EDTA-clearance), albuminuria and 24-h blood pressure were determined. The CYP11B2 -344T/C polymorphism was determined by standard polymerase chain reaction (PCR). RESULTS: The TT, CT and CC genotypes were found in 28 %, 58 % and 14 % of patients, respectively. At baseline albuminuria and blood pressure did not differ between genotype groups. Plasma aldosterone levels (geometric mean (95 % CI)) were similar at baseline: 87 (60-125), 77 (53-112), and 89 (49-161) pg mL(-1) and during follow-up (not significant). After initiation of losartan treatment, comparable mean (SE) reductions in blood pressure and albuminuria were seen in patients with TT, CT and CC genotypes (p >0.6 between groups). After long-term follow-up, there was a tendency towards a difference in systolic blood pressure reduction (p = 0.07, one-way ANOVA), suggesting a poorer response in patients with the CC genotype. No significant difference in rate of decline in GFR (median (range)) was seen between groups (TT, CT, CC): 4.2 (-1.0 to 16.0), 3.2 (-1.6 to 13.8) and 2.6 (-0.1 to 11.0) mL min(-1)year(-1), respectively (p = 0.5). CONCLUSIONS: Compared to a previous smaller study of angiotensin II receptor blockade in essential hypertension, we could not confirm that CYP11B2 -344T/C genotypes contribute towards explaining the observed variability in response to treatment with angiotensin II receptor blockers, which could be due to lack of power.

Dual blockade of the renin-angiotensin-aldosterone system in diabetic nephropathy: the role of aldosterone.

Dual blockade of the renin-angiotensin-aldosterone system (RAAS) with both ACE inhibitors and angiotensin II receptor-blockers has been shown to reduce both albuminuria and blood pressure compared to either monotherapy. The mechanisms behind these beneficial effects are not known, and we hypothesized that the effect of dual RAAS blockade may be due to a more complete suppression of circulating aldosterone. We performed a combined analysis on three randomized, double-masked, cross-over trials where 51 type 1 diabetic patients suffering from diabetic nephropathy received 8 weeks of dual RAAS blockade using an angiotensin II receptor blocker in combination with an ACE inhibitor and 8 weeks of monotherapy with the same ACE inhibitor. Albuminuria, 24 h blood pressure, GFR, and plasma aldosterone were determined at the end of each treatment period. Compared to ACE inhibition alone, dual RAAS blockade lowered blood pressure by 7/5 mm Hg from 137/76 mm Hg, decreased albuminuria by 37% from 558 mg/24 hour, and reduced plasma aldosterone by 28% from 59 pg/ml and caused a reversible decline in GFR of 4 ml/min/1.73 m2 (p < or = 0.01 for all comparisons). There was and a significant correlation between changes in 24-hour diastolic blood pressure and changes in albuminuria. Furthermore, the antialbuminuric response to dual blockade was influenced by the ACE/ID polymorphism, that is, patients carrying the D-allele had a significantly lower reduction of 31% compared to the 55% in patients with the II genotype (p = 0.021). Multiple linear regression analysis revealed that ACE/ID genotypes and reduction in plasma aldosterone, diastolic blood pressure and GFR is associated with changes in albuminuria on dual blockade treatment (R2 (adjusted) = 0.57, p < 0.001). Dual RAAS blockade is a new treatment concept that may offer additional cardiovascular and renal protection in type 1 diabetic patients with diabetic nephropathy. The beneficial response may be influenced by genetic factors and reductions in blood pressure and plasma aldosterone concentrations.

Aldosterone escape during blockade of the renin-angiotensin-aldosterone system in diabetic nephropathy is associated with enhanced decline in glomerular filtration rate.

AIMS/HYPOTHESIS: It has been suggested that aldosterone plays a role in the initiation and progression of renal disease independently of arterial blood pressure and plasma angiotensin II levels. We evaluated the influence of plasma aldosterone levels on progression of diabetic nephropathy during long-term blockade of the renin-angiotensin-aldosterone system. METHODS: A total of 63 hypertensive patients with type 1 diabetes and diabetic nephropathy were treated with losartan, 100 mg once daily, for a mean follow-up period of 35 months. Plasma aldosterone, GFR, albuminuria and 24-h blood pressure were determined at baseline and at regular intervals during the study. RESULTS: Patients were divided according to their increasing or decreasing levels of plasma aldosterone during long-term losartan treatment in an escape group (n=26) and a non-escape group (n=37). In the escape group, aldosterone levels increased from (geometric mean [95% CI]) 57 pg/ml (43-76 pg/ml) at 2 months, to 102 pg/ml (78-134 pg/ml) at the end of the study (p<0.01). The corresponding levels in the non-escape group were 83 pg/ml (69-102 pg/ml) and 49 pg/ml (40-60 pg/ml; p<0.01). The median rate of decline in GFR was 5.0 ml.min(-1).year(-1) (range 0.4-15.9 ml.min(-1).year(-1)) in the escape group, compared with 2.4 ml.min(-1).year(-1) (-1.6 to 11.0 ml.min(-1).year(-1)) in the non-escape group (p<0.005). The increase in plasma aldosterone correlated with the rate of decline in GFR (r(2)=0.19, p<0.001), corresponding to a decline in GFR of 1.5 ml.min(-1).year(-1) for every two-fold increase in plasma aldosterone. Pre-treatment and treatment values of plasma aldosterone were not related to albuminuria or to changes in albuminuria during the study. CONCLUSIONS/INTERPRETATION: Our data suggest that aldosterone escape during long-term blockade of the renin-angiotensin-aldosterone system is associated with an enhanced decline in GFR in patients with type 1 diabetes and diabetic nephropathy.