Association of urinary angiotensinogen with renal arteriolar remodeling in chronic kidney disease.

OBJECTIVE: Renin-angiotensin system (RAS) might be associated with arteriolar remodeling. The present study aimed to explore the hitherto unknown relationship between renal RAS and renal arteriolar remodeling and to elucidate whether altered renal RAS subsequently affects renal function in patients with chronic kidney disease (CKD). METHODS: In this retrospective study, patients with various CKDs not using RAS inhibitors who underwent renal biopsy were included in cross-sectional and longitudinal analyses. Urinary angiotensinogen (UAGT) levels and wall/lumen ratio (WLR) were determined to evaluate renal RAS and renal arteriolar remodeling, respectively. The association between ln(UAGT) and ln(WLR) was cross-sectionally examined using a liner regression model. Furthermore, the association of ln(UAGT) with subsequent changes in estimated glomerular filtration rate (eGFR) per year were longitudinally examined in the largest subgroup of patients who were diagnosed with IgA nephropathy. RESULTS: In the overall cohort (n = 54), the median age, blood pressures, eGFR, and WLR were 37 years, 120/73 mmHg, 85 ml/min per 1.73 m2, and 0.93, respectively. Ln(UAGT) was significantly and positively associated with ln(WLR) even after adjusting for classical and nonclassical clinical renal risk factors. In patients with IgA nephropathy, higher ln(UAGT) was associated with higher ln(WLR). Ln(UAGT) also tended to be associated with a greater decline in eGFR per year over a median period of 8.7 years, even after adjusting for potential confounding factors. CONCLUSION: In patients with CKD, renal RAS might be associated with renal arteriolar remodeling and future decline in eGFR, independent of potential risk factors.

A high normal ankle-brachial index is associated with biopsy-proven severe renal small artery intimal thickening and impaired renal function in chronic kidney disease.

A significant relationship has been established between central hemodynamics and renal microvascular damage. We hypothesized that the increase in the ankle-brachial index (ABI) with age is due to increased arterial stiffness and wave reflection and is thus associated with the pathogenesis of the renal small artery in patients with chronic kidney disease (CKD). We recruited 122 patients with CKD (stages 1-5) who underwent renal biopsy and ABI measurements between 2010 and 2013. Renal small artery intimal thickening (SA-IT) severity was assessed by semiquantitative grading. The median age was 47 years, with a range of 15-86 years (47% women). The median estimated glomerular filtration rate (eGFR) was 62 mL/min/1.73 m2. Compared with patients with the lowest 1-3 SA-IT index quartile, those with the highest quartile of the SA-IT index were older in age had higher mean arterial pressure, ABI, brachial-ankle pulse wave velocity, and lower eGFR. ABI was positively associated with SA-IT severity and inversely associated with eGFR. Multivariate logistic regression analyses showed that ABI was significantly associated with the highest quartile of the SA-IT index (odds ratio per SD increase in ABI, 1.83; 95% confidence interval, 1.08-3.26) and low eGFR (<60 mL/min/1.73 m2) (odds ratio per SD increase in ABI, 1.74; 95% confidence interval, 1.03-3.03). In conclusion, a high normal ABI was associated with severe renal small artery intimal thickening and low eGFR in patients with CKD.

Augmented Association Between Blood Pressure and Proteinuria in Hyperuricemic Patients With Nonnephrotic Chronic Kidney Disease.

BACKGROUND: Hyperuricemia (HU) may enhance susceptibility to hypertensive renal damage via disrupted autoregulation of glomerular hemodynamics. The effect of HU on the association between blood pressure (BP) and proteinuria remains unknown in patients with chronic kidney disease (CKD). METHODS: In total, 109 patients with nonnephrotic CKD (55 men and 54 females) who underwent renal biopsy were recruited. Arteriolar hyalinosis was semiquantitatively assessed via arteriole grading. Correlation between BP and urine protein (UP) level was examined based on the presence of HU, which was defined as the use of urate-lowering drugs or serum uric acid levels of ≥7 and ≥5 mg/dl in males and females, respectively, which were associated with increased risks of hyalinosis in our previous study. RESULTS: Median age, BP, estimated glomerular filtration rate, and UP level were 38 years, 124/74 mm Hg, 82 ml/min/1.73 m2, and 0.8 g/gCr, respectively. In patients with HU (n = 59), log-transformed systolic BP (SBP) was significantly correlated with log-transformed UP level (r = 0.49, P < 0.0001); this was not observed in patients without HU (n = 50). Multiple regression analysis (R2 = 0.21, P = 0.0001) revealed that the interaction between HU and log-transformed SBP with respect to proteinuria was significantly correlated with log-transformed UP level (ß = 7.0, P = 0.03), independent of age, sex, and potential confounding factors; however, this statistical significance was completely eliminated after adjustment for the arteriolar hyalinosis index. CONCLUSIONS: HU potentiates susceptibility to hypertensive glomerular damage via disrupted autoregulation in patients with nonnephrotic CKD.

Modification of the impact of hypertension on proteinuria by renal arteriolar hyalinosis in nonnephrotic chronic kidney disease.

OBJECTIVE: Morphological analysis suggests that afferent arteriole hyalinosis reflects disturbed autoregulation of glomerular hemodynamics. However, the effect of arteriolar hyalinosis on the correlation between blood pressure (BP) levels and proteinuria is unknown in patients with chronic kidney disease (CKD). Therefore, we conducted a cross-sectional study to determine this correlation. METHODS: A total of 109 patients with nonnephrotic CKD (55 men and 54 women) who underwent renal biopsy were recruited. Arteriolar hyalinosis was semiquantitatively assessed via arteriole grading. We examined the correlation between BP and urine protein levels (g/gCr) according to the presence of arteriolar hyalinosis. RESULT: Patients had a mean age, BP, estimated glomerular filtration rate, and urine protein level of 40 years, 126/75 mmHg, 86 ml/min per 1.73 m, and 1.3 g/gCr, respectively. Patients with hyalinosis (n = 59) exhibited significant increases in median proteinuria (g/gCr) because the SBP increased (<130, 130-140, and ≥140 mmHg: 1.0, 1.3, and 2.3, respectively; P = 0.045); however, median proteinuria was comparable in patients without hyalinosis (n = 50), regardless of SBP. Multiple logistic analysis revealed that combined high BP and hyalinosis were significantly associated with increased proteinuria, defined as equal to or greater than the median value (odds ratio: 5.99, 95% confidence interval: 1.13-31.70, P < 0.05 vs. high BP-/hyalinosis-). Moreover, this combination was associated with the largest glomerular diameter. CONCLUSION: Renal arteriolar hyalinosis may potentiate susceptibility to BP-related glomerular damage in patients with nonnephrotic CKD. Dysregulated afferent arteriolar resistance via arteriolar sclerosis may affect hypertensive renal damage.

Interrelationship between brachial artery function and renal small artery sclerosis in chronic kidney disease.

Chronic kidney disease (CKD), characterized by senile inflammation, is a risk factor for cardiovascular disease. Conduit artery function and small artery structure relate to cardiovascular disease. We examined the correlations, determinants and interrelationships of arterial indices in association with CKD in a cross-sectional study of 139 patients (60% male; mean age 44 years) with CKD (stages 3-5, 39%) who underwent a renal biopsy. Conduit artery function and small artery sclerosis were assessed by brachial artery flow-mediated dilatation (FMD) and semiquantitative evaluation of small artery intimal thickening (SA-IT), respectively. The estimated glomerular filtration rate correlated with FMD (r=0.31, P=0.0002) and inversely correlated with SA-IT (r=-0.54, P<0.0001). Multiple regression analysis showed that FMD was inversely correlated with SA-IT and vice versa. In addition, high-sensitivity C-reactive protein (hs-CRP) was significantly correlated with SA-IT, but not FMD. Multiple logistic analysis revealed that higher hs-CRP concomitant with decreased FMD was further associated with the risk of severe SA-IT compared with their individual effects. These findings suggest that both conduit artery and small artery disease develop with mutual interaction in parallel with decreased kidney function. Coexistence of inflammation and conduit artery dysfunction may be closely related to renal small artery sclerosis in patients with CKD.

Hypertriglyceridemia accompanied by increased serum complement component 3 and proteinuria in non-nephrotic chronic kidney disease.

BACKGROUND: Hypertriglyceridemia (hTG) is a risk factor for progression of chronic kidney disease (CKD); however, it remains unknown whether the adipocytokine complement component 3 (C3) is involved in the association between hTG and CKD. METHODS: The study included 138 patients (54 % male) with non-nephrotic (serum albumin ≥3 g/dl) CKD who had undergone a renal biopsy and did not have hypocomplementemic disease. Renal arteriolopathy was assessed semi-quantitatively. We examined the cross-sectional associations between proteinuria and hTG with or without a higher serum C3 level (hC3), defined as equal or above the median value. RESULTS: The mean (SD) age of the patients was 42 (±17) years and urine protein was 1.2 (±1.2) g/gCr. Patients with hTG had a significantly higher urine protein than those without hTG. Subgroup analysis showed that the hTG+/hC3+ group had higher grade arteriolopathy and urine protein levels. Multiple logistic regression analysis adjusted for age, sex, and diabetes mellitus showed that hC3+ alone was associated significantly with higher levels of urine protein [odds ratio (OR), 2.98; 95 % confidence interval (CI) 1.19-7.46, p = 0.02]; however, hTG alone showed no such association. hTG+/hC3+ was a significant factor when hTG-/hC3- was used as the reference (adjusted OR 5.32; 95 % CI 1.40-20.17, p = 0.01), with this OR being decreased by adjustment for arteriolopathy. CONCLUSIONS: hTG accompanied by hC3 was associated with proteinuria in non-nephrotic CKD. Arteriolopathy may influence this association. A prospective study is needed to determine the predictive value of this association in CKD progression.

An association between uric acid levels and renal arteriolopathy in chronic kidney disease: a biopsy-based study.

Uric acid (UA) can induce renal arteriolopathy in animal models. Whether there is an association between UA and renal arteriolopathy in patients with chronic kidney disease (CKD) is unknown. Here, we examined the cross-sectional association of serum UA levels with renal arteriolar hyalinosis and wall thickening. Arteriolar parameters were assessed by semiquantitative grading (max: grade 3) of arterioles in 167 patients with CKD (mean age, 42.4 years; 86 men and 81 women) who underwent renal biopsy. The mean serum UA level was 6.4 mg dl(-1). We observed hyalinosis in 94 patients (56%) and wall thickening in 119 patients (71%). As the UA level tertile increased, the proportion of higher-grade (grade 2 and 3) hyalinosis and wall thickening increased (hyalinosis, P<0.0001 and wall thickening, P=0.0002, for trend). Multiple logistic analysis adjusted for age ≥40 years, sex, hypertension status, diabetes mellitus status and estimated glomerular filtration rate <60 ml min(-1) per 1.73 m(2) showed that hyperuricemia (UA ≥7 mg dl(-1)) was significantly associated with a higher risk of hyalinosis (adjusted odds ratio: 3.13; 95% confidence interval: 1.23-7.94; P=0.02) and higher-grade (equal to or higher than the mean value) wall thickening (adjusted odds ratio: 2.66; 95% confidence interval: 1.11-6.38; P=0.03). Hence, these results suggest that hyperuricemia may be related to renal arteriolar damage in patients with CKD.