Night-time activation of the intrarenal renin–angiotensin system due to nocturnal hypertension is associated with renal arteriosclerosis in normotensive IgA nephropathy patients

Effects of Nondipping Blood Pressure Changes: A Nephrologist Prospect

Blood pressure (BP) variations depend on various internal, environmental, and behavioral factors. BP fluctuations occur both in normotensive and hypertensive people. Although it fluctuates over the 24-hr day and night, the morning BP increases after waking up and declines throughout sleep. It is typical for BP to decrease by 10% to 20%, while sleeping, known as dipping BP. However, if there is no decrease in nighttime mean systolic BP or a drop of less than 10 mmHg, it is called nondipping BP. Conversely, reverse dipping BP means an increase in mean systolic BP instead of a drop during the night. Reverse dipping is observed in hypertension (HTN), diabetes mellitus (DM), chronic kidney disease (CKD), and obstructive sleep apnea (OSA) syndrome. The introduction of ambulatory BP monitoring (ABPM) led to the emergence of identifying normal and elevated BP patterns. Non-dipping BP increases the risk of cardiovascular system (CVS) complications such as left ventricular hypertrophy, proteinuria, glomerular filtration rate (GFR) reduction, and CKD progression. A loss or blunting of the normal BP profile is recognized as a deleterious variant, and restoring abnormal BP patterns has been reported to significantly impact end-organ damage, morbidity, and mortality. In this non-systematic clinically-oriented, comprehensive review, we aim to update the BP variables and the pathophysiology of nondipping BP and point out the areas which need more investigation from a nephrology perspective because the nondipping BP increases the risk of proteinuria, GFR reduction, and CKD progression. A literature search of PubMed, Google, EMBASE, and Google Scholar was conducted. Checks of selected papers and relevant reviews complemented the electronic search. With improved BP measurement methods, the physiology of BP profile variations is readily detectable during the day and night. A nondipping BP profile is a distinct BP pattern that may have significant end-organ damage effects and therapeutic importance for nephrologists. The pathophysiology of the nondipping BP variant must be clarified to prevent complications, and further investigations are required. Furthermore, there is debate about the best BP index to utilize: systolic BP, diastolic BP, mean arterial pressure, or a mixture of all. All these areas are important and need new research projects.

Clinicopathological Features of Gitelman Syndrome with Proteinuria and Renal Dysfunction

INTRODUCTION

Gitelman syndrome (GS) is a rare renal tubular salt-wasting disorder. Besides kidney electrolyte loss, proteinuria and renal dysfunction were also observed. However, their incidence, risk factors, pathological features, and prognosis were unclear.

METHODS

We retrospectively reviewed 116 GS patients and analyzed their clinical, genetic, and pathological characteristics. We also systematically reviewed articles on GS with proteinuria and renal dysfunction.

RESULTS

Twenty-three GS patients had proteinuria (69.6%) and renal dysfunction (43.5%) with a mean age of 35.3 ± 13.2 years, and 65.2% were male. Compared to patients without proteinuria or renal dysfunction, these patients had elevated plasma angiotensin II level (440.2 ± 351.7 vs. 253.2 ± 187.4 pg/mL, p = 0.031) and three times higher incidence of diabetes. The renal pathology of nine biopsied patients indicated hypertrophy of the juxtaglomerular apparatus (100%), chronic tubulointerstitial changes (66.7%), intrarenal vascular changes (66.7%), and glomerulopathy (55.6%). More extensive renin staining was observed in patients with GS than in the control group with glomerular minor lesion (p < 0.001). During a median of 85 months (range, 11-205 months) of follow-up for 19 out of the 23 GS-renal patients, the renal function was generally stable, except one died of cancer and one developed end-stage renal disease because of concomitant membranous nephropathy and IgA nephropathy.

CONCLUSION

Proteinuria and renal dysfunction were more common than expected and might indicate glomerulopathy and vascular lesions besides a tubulointerstitial injury in GS. Renal function may maintain stable with effective therapy in most cases.

Normotensive non-dipping blood pressure profile does not predict the risk of chronic kidney disease progression

The lack of a decrease in nocturnal blood pressure is a risk factor for the progression of chronic kidney disease (CKD); however, it currently remains unknown whether it is a risk factor in normotensive CKD patients. We conducted a retrospective cohort study and enrolled 676 CKD patients who underwent ambulatory blood pressure monitoring (ABPM). According to their nocturnal blood pressure dipping pattern (>10%: dipper or <10%: non-dipper) and average 24-h systolic blood pressure (>130/80 mmHg: hypertension or <130/80 mmHg: normotension), patients were divided into four groups. The estimated glomerular filtration rate (eGFR) decline over 2 years and relevant clinical parameters were analyzed among groups. Among all participants, 82.7% were non-dippers and half of them were normotensive. The eGFR decline was the most rapid in hypertensive non-dipper patients (4.73 ± 0.45 ml/min/1.73 m²/2 years), and was not significantly different between normotensive non-dipper (1.31 ± 0.49 ml/min/1.73 m²/2 years) and dipper patients (1.69 ± 0.80 ml/min/1.73 m²/2 years). A multivariate regression analysis revealed that the amount of urinary protein (95% confidence interval (CI): 1.51-2.63), 24-h systolic blood pressure (95% CI 1.13-1.45), and eGFR (95% CI 1.02-1.44) were associated with a rapid eGFR decline. We conclude that, according to the ABPM-based analysis, a non-dipping blood pressure pattern in normotensive CKD patients does not predict the risk of a rapid decline in eGFR. This suggests that the control of blood pressure, rather than its circadian rhythm, is essential for the preservation of eGFR.

[Correlation between TGF-B gene promoter-509C/T polymorphism and IgA nephropathy in core families in Guangxi Zhuang Autonomous Region and the therapeutic effect of dendrobium]

OBJECTIVE

To investigate the correlation between transformation growth factor (TGF- B) polymorphisms and IgA nephropathy and the therapeutic effect of dendrobium on IgA nephropathy.

METHODS

Polymerase chain reaction- restriction fragment length polymorphism (PCR- RFLP) and direct sequencing were used for analysis of 118 patients with IgA nephropathy from core families in Guangxi Zhuang Autonomous Region. The imbalanced transfer of TGF iso1-509 C/T in the affected offsprings was observed by transfer imbalance test and HRR analysis. The TGF-B genotype of the patients and the core family members were detected. The therapeutic effects of Dendrobium candidum combined with hormone and ACEI/ARB treatments were evaluated by observing the patient's urine protein (24 hUpr), serum albumin (ALB), creatinine (Scr) and urea nitrogen (BUN) levels.

RESULTS

In the 118 patients with IgA nephropathy, we identified TGF-B 1 promoter -509C/T genotype CC in 32 (27.1%) cases, CT in 58 (49.2%) cases, and TT in 28 (23.7%) cases. In the core family of the patients, CC genotype was found in 33 (28.0%) cases, CT in 55 (46.6%) cases, and TT in 30 (28.0%) cases. The treatments significantly lowered 24 hUpr, Scr, and BUN levels (P > 0.05) in patients with CC genotype, significantly lowered 24 hUpr and BUN levels in patients with CT genotype (P < 0.05), and significantly lowered 24 hUpr and BUN level and increased (P < 0.05) ALB level (P < 0.01) in patients with TT genotype.

CONCLUSIONS

There is no significant correlation between TGF-B promoter - 509C/T polymorphism and IgA nephropathy. The patients with CC genotype are sensitive to the treatments with hormone and ACEI/ ARB and show a stronger response to combined treatments with dendrobium.