Association between serum uric acid level and renal arteriolar hyalinization in individuals without chronic kidney disease

Impacts of Febuxostat on Cerebral and Cardiovascular Events in Elderly Patients with Hyperuricemia: Post Hoc Analysis of a Randomized Controlled Trial

A recent meta-analysis found no benefit of uric acid-lowering therapy including febuxostat on death, cardiovascular events, or renal impairment. However, there may be populations that benefit from febuxostat in reducing mortality and cerebral and cardiovascular events. The aim of the present study was to examine the clinical benefit of febuxostat in elderly patients stratified by age using Febuxostat for Cerebral and CaRdiorenovascular Events PrEvEntion StuDy (FREED) data. FREED was a randomized study involving patients aged 65 years or older with hyperuricemia and risk factors for cerebral, cardiovascular, or renal diseases. A total of 1,070 patients were included in this post hoc analysis, divided into 2 age groups: 65-74 years and ≥ 75 years. Patients were randomized into febuxostat and non-febuxostat groups, with uric acid levels monitored for 36 months. The primary composite end point included cerebral, cardiovascular, and renal events. In patients aged between 65 and 74 years, febuxostat significantly reduced the risk of future cerebral and cardiorenovascular events. However, no effects of febuxostat were found in the older population aged ≥ 75 years. Heterogeneity in potential interactions between the age and febuxostat treatment was particularly observed in non-fatal cerebral and cardiovascular events and all-cause death. Patients aged ≥ 75 years exhibited more pre-existing factors associated with cerebral and cardiorenovascular events than those aged 65-74 years. The effectiveness of febuxostat varies by age group, with potential benefits for patients aged 65-74 years. The effects of febuxostat are complex and it is important to consider patient characteristics in its clinical use.

Association between Hemoglobin A1c and Renal Arteriolar Sclerosis in Subjects Presenting without any Apparent Kidney Dysfunction

AIMS

Diabetic kidney disease is a major vascular complication in patients with diabetes mellitus (DM). However, the association between the hemoglobin (Hb)A1c levels, notably the prediabetic levels, and renal pathological changes remains unclear. We investigated the association between the HbA1c levels and renal arteriolar lesions in subjects without any apparent kidney dysfunction using a living kidney donor cohort.

METHODS

Between January 2006 and May 2016, 393 living kidney donors underwent a "zero-time" biopsy at Kyushu University Hospital. The patients were divided into four groups (HbA1c levels ＜5.6%, 5.6%-5.7%, 5.8%-6.4%, and ≥ 6.5%, or diagnosed with DM [DM group]). Renal arteriolar hyalinization and wall thickening were assessed using semi-quantitative grading. We then investigated the association between the HbA1c levels and renal pathological changes.

RESULTS

158 (40.2%) patients had arteriolar hyalinization and 148 (37.6%) showed wall thickening. A significant correlation was observed between the HbA1c levels and wall thickening (p for trend ＜0.001). An elevated HbA1c level was significantly associated with wall thickening according to a multivariable logistic analysis in subjects with HbA1c levels of 5.6%-5.7% and 5.8%-6.4%, and the DM group, compared with those with HbA1c levels of ＜5.6% (odds ratio [OR], 1.91; 95% confidence interval [CI]: [1.03-3.54] for 5.6%-5.7%, OR, 1.96; 95% CI: [1.09-3.53] for 5.8%-6.4%, and OR, 2.86; 95% CI: [0.91-9.01] for the DM group), whereas arteriolar hyalinization did not increase within the nondiabetic HbA1c levels.

CONCLUSIONS

Elevated high-normal HbA1c levels are considered to be independent risk factors for arteriolar wall thickening. Subclinical renal arteriolar sclerosis may develop in patients with prediabetic HbA1c levels.

Cumulative smoking dose is associated with subclinical renal injury: a pathological study in individuals without chronic kidney disease

BACKGROUND

Epidemiological studies have identified smoking as an independent risk factor for development of chronic kidney disease. However, the early renal pathological lesions have not been clearly elucidated.

METHODS

We investigated time-zero biopsy specimens from 547 living kidney donors and evaluated the relationships between smoking and renal histological changes, including arteriolar hyalinization, intimal thickening of small-medium arteries, global glomerulosclerosis, and interstitial fibrosis and tubular atrophy (IF/TA).

RESULTS

A total of 199 subjects (36.4%) had smoking history; 92 (16.8%) and 107 (19.6%) subjects had <20 pack-years and ≥20 pack-years of smoking, respectively. Cumulative smoking dose was significantly associated with prevalence of arteriolar hyalinization: the multivariable-adjusted odds ratio (OR) per 20 pack-year increase was 1.50 (95% confidence interval 1.15-1.97). The ORs for smokers with <20 pack-years and ≥20 pack-years versus never-smokers were 1.76 (1.01-3.09) and 2.56 (1.48-4.44), respectively. Smoking was also associated with prevalence of >10% global glomerulosclerosis: the OR per 20 pack-year increase was 1.24 (0.96-1.59). The ORs for smokers with <20 pack-years and ≥20 pack-years versus never-smokers were 1.50 (0.98-2.78) and 2.11 (1.18-3.79), respectively. The ORs for these pathological changes increased significantly depending on cumulative smoking dose. Intimal thickening of small-medium arteries and IF/TA were not associated with smoking status. The prevalence of arteriolar hyalinization remained higher in patients with ≥10 years since smoking cessation than in never-smokers [OR 2.23 (1.03-4.83)].

CONCLUSIONS

Subclinical pathological injury caused by smoking is potentially associated with renal arteriolar hyalinization and glomerular ischaemia.

Association of blood pressure and hyperuricemia with proteinuria and reduced renal function in the general population

This study aimed to investigate the effect of hyperuricemia (HU) on the association of systolic blood pressure (SBP) with the prevalence of proteinuria and low estimated glomerular filtration rate (eGFR) in the general population. This cross-sectional study enrolled 24,728 Japanese individuals (11,137 men and 13,591 women) who underwent health checkups in 2010. The prevalence of proteinuria and low eGFR (< 60 mL/min/1.73 m2) among participants classified according to serum uric acid levels and SBP was compared. HU was defined as serum uric acid levels higher than the 75th percentile in male and female participants (> 7.2 and > 5.4 mg/dL, respectively). The odds ratio (OR) for proteinuria increased with elevated SBP. This trend was significantly evident in participants with HU. Moreover, there was an interactive effect of SBP and HU on the prevalence of proteinuria in the male (Pfor interaction = 0.04) and female (Pfor interaction = 0.04) participants. Next, we evaluated the OR for low eGFR (< 60 mL/min/1.73 m2) with and without proteinuria based on the presence of HU. The multivariate analysis revealed that the OR for low eGFR with proteinuria increased with elevated SBP, but that for low eGFR without proteinuria decreased. These trends of OR tended to be prevalent among those with HU. The association between SBP and the prevalence of proteinuria was more pronounced in participants with HU. However, the association between SBP and decreased renal function with and without proteinuria might be different regardless of HU.

Progress in Pathological Diagnosis after Kidney Transplantation: Current Trend and Future Perspective

Advances in immunosuppressive therapy; posttransplant management of allograft rejection; and measures against infectious diseases, cardiovascular diseases, and malignancy dramatically improved graft and patient survival after kidney transplantation (KT). Among them, kidney allograft biopsy is an important tool and the gold standard for the diagnosis of various kidney allograft injuries, including allograft rejection, virus-induced nephropathy, calcineurin inhibitor toxicity, and posttransplant glomerular diseases. The Banff Conference on Allograft Pathology has contributed to establishing the diagnostic criteria for kidney allograft rejection and polyomavirus-associated nephropathy that are used as a common standard worldwide. In addition to the for-cause biopsy, many transplant centers perform protocol biopsies in the early and late posttransplant periods to detect and treat allograft injury earlier. Preimplantation biopsy in deceased-donor KT has also been performed, especially in the marginal donor, and attempts have been made to predict the prognosis in combination with clinical information and the renal resistance of hypothermic machine perfusion. Regarding the preimplantation biopsy from a living kidney donor, it can provide useful information on aging and/or early changes in lifestyle diseases, such as glomerulosclerosis, tubulointerstitial changes, and arterial and arteriolar sclerosis, and be used as a reference for the subsequent management of living donors. In this review, morphologic features of important kidney allograft pathology, such as allograft rejection and polyomavirus-associated nephropathy, according to the latest Banff classification and additional information derived from protocol biopsy, and future perspectives with recently developed technologies are discussed.

Long-term impact of baseline serum uric acid levels on living kidney donors: a retrospective study

BACKGROUND

Preoperative characteristics of living kidney donors are commonly considered during donor selection and postoperative follow-up. However, the impact of preoperative uric acid (UA) levels is poorly documented. The aim of this study was to evaluate the association between preoperative serum UA levels and post-donation long-term events and renal function.

METHODS

This was a single-center retrospective analysis of 183 living kidney donors. The donors were divided into high (≥5.5 mg/dl) and low (< 5.5 mg/dl) UA groups. We analyzed the relationship between preoperative UA levels and postoperative estimated glomerular filtration rate (eGFR), as well as adverse events (cardiovascular events and additional prescriptions for hypertension, gout, dyslipidemia, and diabetes mellitus), over 5 years after donation.

RESULTS

In total, 44 donors experienced 52 adverse events over 5 years. The incidence of adverse events within 5 years was significantly higher in the high UA group than in the low UA group (50% vs. 24%, p = 0.003); this was true even after the exclusion of hyperuricemia-related events (p = 0.047). UA emerged as an independent risk factor for adverse events (p = 0.012). Donors with higher UA levels had lower eGFRs after donation, whereas body mass index, hemoglobin A1c, blood pressure, and low-density lipoprotein cholesterol did not have any impact on the eGFR.

CONCLUSIONS

The findings suggest that preoperative UA levels should be considered during donor selection and postoperative follow-up.

Is microvascular dysfunction a systemic disorder with common biomarkers found in the heart, brain, and kidneys? - A scoping review

Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and 2019 that measured blood biomarkers of MVD in three vital organs i.e. brain, heart, and the kidney. Of the 9706 unique articles 321 met the criteria, reporting 49 biomarkers of which 16 were common to the three organs. Endothelial dysfunction, inflammation including reactive oxidation, immune activation, and coagulation were the commonly recognized pathways. Triglyceride, C-reactive protein, Cystatin C, homocysteine, uric acid, IL-6, NT-proBNP, thrombomodulin, von Willebrand Factor, and uric acid were increased in MVD of all three organs. In contrast, vitamin D was decreased. Adiponectin, asymmetric dimethylarginine, total cholesterol, high-density and low-density cholesterol were found to be variably increased or decreased in studies. We review the pathways underlying MVD in the three organs and summarize evidence supporting its systemic nature. This scoping review informs clinicians and researchers in the multi-system manifestation of MVD. Future work should focus on longitudinal investigations to evaluate the multi-system involvement of this disease.