Nocturnal and Circadian Rhythm of Blood Pressure Is Associated with Renal Structure Damage and Function in Patients with IgAN

Irbesartan ameliorates diabetic kidney injury in db/db mice by restoring circadian rhythm and cell cycle

Background and Objectives

Irbesartan has been widely used in the clinical treatment of diabetic kidney disease (DKD). However, the molecular mechanism of its delay of DKD disease progression has not been fully elucidated. The aim of the present study was to investigate the mechanism of irbesartan in the treatment of DKD.

Materials and Methods

C57BL/KsJ db/db mice were randomly divided into the model group and irbesartan-treated group. After treatment with irbesartan for 12 weeks, the effects on blood glucose, body weight, 24-h urinary albumin, and renal injuries were evaluated. Microarray was used to determine the differentially expressed genes (DEGs) in the renal cortex of mice. |Log FC| <0.5 and false discovery rate (FDR) <0.25 were set as the screening criteria. Kyoto Encyclopedia of Genes and Genomes (KEGG), gene ontology (GO), protein-protein interaction (PPI) network and modules, and microRNA (miRNA)-DEGs network analysis were applied to analyze the DEGs. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the results of microarray.

Results

The present study demonstrated irbesartan could significantly improve the renal function in db/db mice through decreasing 24-h urinary albumin and alleviating the pathological injury of kidney. Irbesartan may affect the expression of numerous kidney genes involved in circadian rhythm, cell cycle, micoRNAs in cancer, and PI3K-AKT signaling pathway. In the miRNA-DEGs network, miR-1970, miR-703, miR-466f, miR-5135, and miR-132-3p were the potential targets for irbesartan treatment. The validation test confirmed that key genes regulating circadian rhythm (Arntl, Per3, and Dbp) and cell cycle (Prc1, Ccna2, and Ccnb2) were restored in db/db mice on treatment with Irbesartan.

Conclusion

Generally, irbesartan can effectively treat DKD by regulating the circadian rhythm and cell cycle. The DEGs and pathways identified in the study will provide new insights into the potential mechanisms of irbesartan in the treatment of DKD.

Irbesartan ameliorates diabetic kidney injury in db/db mice by restoring circadian rhythm and cell cycle

Background and Objectives

Irbesartan has been widely used in the clinical treatment of diabetic kidney disease (DKD). However, the molecular mechanism of its delay of DKD disease progression has not been fully elucidated. The aim of the present study was to investigate the mechanism of irbesartan in the treatment of DKD.

Materials and Methods

C57BL/KsJ db/db mice were randomly divided into the model group and irbesartan-treated group. After treatment with irbesartan for 12 weeks, the effects on blood glucose, body weight, 24-h urinary albumin, and renal injuries were evaluated. Microarray was used to determine the differentially expressed genes (DEGs) in the renal cortex of mice. |Log FC| <0.5 and false discovery rate (FDR) <0.25 were set as the screening criteria. Kyoto Encyclopedia of Genes and Genomes (KEGG), gene ontology (GO), protein-protein interaction (PPI) network and modules, and microRNA (miRNA)-DEGs network analysis were applied to analyze the DEGs. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the results of microarray.

Results

The present study demonstrated irbesartan could significantly improve the renal function in db/db mice through decreasing 24-h urinary albumin and alleviating the pathological injury of kidney. Irbesartan may affect the expression of numerous kidney genes involved in circadian rhythm, cell cycle, micoRNAs in cancer, and PI3K-AKT signaling pathway. In the miRNA-DEGs network, miR-1970, miR-703, miR-466f, miR-5135, and miR-132-3p were the potential targets for irbesartan treatment. The validation test confirmed that key genes regulating circadian rhythm (Arntl, Per3, and Dbp) and cell cycle (Prc1, Ccna2, and Ccnb2) were restored in db/db mice on treatment with Irbesartan.

Conclusion

Generally, irbesartan can effectively treat DKD by regulating the circadian rhythm and cell cycle. The DEGs and pathways identified in the study will provide new insights into the potential mechanisms of irbesartan in the treatment of DKD.

Differential expression of transfer RNA-derived small RNAs in IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is one of the most common forms of primary glomerulonephritis. Recent studies have indicated that small noncoding RNAs, such as tRNA-derived small RNAs (tsRNAs), might be novel biomarkers for glomerulonephritis. We therefore investigated the potential roles and possible functions of the tsRNAs in IgAN.

METHOD

Peripheral blood mononuclear cells (PBMCs) were extracted from blood samples of the patients with IgAN and healthy control groups. The expression profiles of tsRNAs were assessed by small RNA sequencing (RNA-Seq) in PBMCs of the IgAN and control groups. Dysregulated tsRNAs were selected for validation by quantitative real-time polymerase chain reaction (qRT-PCR). Target gene prediction and enrichment were performed by bioinformatics analysis.

RESULTS

The results revealed that 143 significantly upregulated and 202 significantly downregulated tsRNAs were differentially altered in the IgAN group compared with the control group. Five upregulated tsRNAs (tRF-Val-AAC-007, tRF-Ala-AGC-063, tRF-Gln-CTG-010, tRF-Tyr-GTA-011 and tRF-Thr-AGT-007) and 3 downregulated tsRNAs (tiRNA-Val-TAC-004, tRF-Gly-CCC-005 and tRF-His-GTG-006) were selected for validation by qRT-PCR; the results were consistent with the sequencing data. Gene Ontology (GO) analysis revealed that the target genes predicted by upregulated tsRNAs were mostly enriched in "nucleic acid metabolic process,' "intracellular part,' and "ion binding,' whereas the target genes predicted by downregulated tsRNAs were mostly enriched in "regulation of cellular component organization,' "membrane-bound organelle,' and "ion binding.' Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that the target genes predicted by upregulated tsRNAs were mostly enriched in "herpes simplex virus 1 infection,' whereas the target genes predicted by downregulated tsRNAs were mostly enriched in "circadian rhythm CONCLUSIONS:: The present study confirmed the differential expression of tsRNAs in patients with IgAN, and these dysregulated tsRNAs might be novel potential targets for the diagnosis and treatment of IgAN.

[Antihypertensives always evenings-absolutely not or sensible?]

The Spanish Hygia study has led to considerable irritation due to the general recommendation to prescribe antihypertensives preferably to be taken in the evening, especially since the lay press as well as medical media made enthusiastic comments. The discussion about the optimal time to take antihypertensive drugs shows once again how dangerous the uncritical handling of study data can be. No possible risks were pointed out. The Hygia study compared 19,084 patients with morning and evening intake of antihypertensive drugs under the control of a 48‑h blood pressure measurement (!). There was a significantly better reduction in blood pressure and the rate of cardiovascular and cerebrovascular events with evening intake. The data are scientifically valuable; however, the conclusions are incomprehensible based on the data, contradict many other studies and are dangerous for certain patient groups. There are also methodological shortcomings. Therefore, a general evening intake is not justified and nonsensical due to the diverse, individually very different pathophysiological findings of the nocturnal blood pressure behavior. Basically, the outpatient 24‑h blood pressure measurement (ABPM) enables a better assessment of the individual cardiovascular and cerebrovascular risks and prevents an incorrect assessment of the blood pressure and thus unnecessary or sufficient treatment. Instead of a general recommendation, the ABPM offers the option of an individually tailored treatment. Taking antihypertensive drugs in the evening should always be preceded by an ABDM in the case of prognostically unfavorable nocturnal hypertension in order to avoid the risk of nocturnal ischemic risks due to excessive drops in blood pressure.

Circadian rhythms and the kidney

Numerous physiological functions exhibit substantial circadian oscillations. In the kidneys, renal plasma flow, the glomerular filtration rate and tubular reabsorption and/or secretion processes have been shown to peak during the active phase and decline during the inactive phase. These functional rhythms are driven, at least in part, by a self-sustaining cellular mechanism termed the circadian clock. The circadian clock controls different cellular functions, including transcription, translation and protein post-translational modifications (such as phosphorylation, acetylation and ubiquitylation) and degradation. Disruption of the circadian clock in animal models results in the loss of blood pressure control and substantial changes in the circadian pattern of water and electrolyte excretion in the urine. Kidney-specific suppression of the circadian clock in animals implicates both the intrinsic renal and the extrarenal circadian clocks in these pathologies. Alterations in the circadian rhythm of renal functions are associated with the development of hypertension, chronic kidney disease, renal fibrosis and kidney stones. Furthermore, renal circadian clocks might interfere with the pharmacokinetics and/or pharmacodynamics of various drugs and are therefore an important consideration in the treatment of some renal diseases or disorders.

A risk prediction model for renal damage in a hypertensive Chinese Han population

Backgroud: While numerous risk factors for renal damage in the hypertensive population have been reported, there is no single prediction model. The purpose of this study was to develop a model to comprehensively evaluate renal damage risk among hypertensive patients. Methods: We analyzed the data of 582 Chinese hypertensive patients from 1 January 2013 to 30 June 2016. Basic patient information was collected along with laboratory test results. According to the albumin-to-creatinine ratio, the subjects were divided into a hypertension with renal damage group and a hypertension without renal damage group. The prediction model was established by logistic regression based on principal component analysis, and the area under the receiver operating characteristic curve was used to evaluate the predictive performance of the model.Results: There are 11 indicators have statistically significant difference between the two groups (P < 0.05); The equation expressed including all 11 risk factors was as follows: Y = (-0.236) - 0.1705 (sex) - 0.0098 (age) - 0.1067 (smoking history) + 0.0303 (drinking history) - 0.3031 (CHD) + 0.1276 (diabetes history) - 0.0596 (CRP level) - 0.0732 (CysC level) + 0.0949 (β2-MG level) + 0.5407 (blood pressure type) + 0.6470 (RRI). The calculated AUC was 74.4%; The risk in males was much higher than that in females of the same age. However, with increasing age, the male:female risk ratio gradually decreased. Conclusion: Eleven  indicators (including sex, age, smoking history, drinking history, coronary heart disease, diabetes history, C-reactive protein, CystatinC,  β2-microglobulin protein, blood pressure type, renal artery resistance index)  may be the risk factors of renal damage in hypertension. Our regression equation provides a feasible means of predicting renal damage in Chinese hypertensive populations, and the model showed good predictive power. In addition, estrogen may confer a protective effect on the kidney. Abbreviations: PCA: principal component analysis; SLPs: synthetic latent predictors; CKD: chronic kidney disease; RRI: renal artery resistance index; MLR: multivariate logistic regression; CHD: coronary heart disease; UACR: urine trace albumin/uric creatinine ratio; CysC: CystatinC; TG: Triglyceride; CHO: cholesterol; HDL: high-density lipoprotein cholesterol; LDL: low-density lipoprotein cholesterol; CRP: C-reactive protein; HCY: homocysteine; UA: uric acid; AUC: area under the ROC curve; CVE: cardiovascular events; RFF: renal function related factor; PHF: personal history related factor; CVF: cardiovascular factor; GMF: glucose metabolism factor; IF: inflammatory factor; BPF: blood pressure factor.

Different Relevance of Peripheral, Central or Nighttime Blood Pressure Measurements in the Prediction of Chronic Kidney Disease Progression in Patients with Mild or No-Proteinuria

BACKGROUND/AIMS

Arterial hypertension is one of the leading factors aggravating the course of chronic kidney disease (CKD). It seems that the novel parameters used in the assessment of the blood pressure (BP) load (i.e. central blood pressure, nighttime blood pressure) may be more precise in predicting the cardiovascular risk and the progression of CKD in comparison with the traditional peripheral blood pressure measurements in the office conditions. The aim of the study was to assess the impact of the central, or nighttime blood pressure on the progression of CKD in patients with mild or no-proteinuria (autosomal, dominant polycystic kidney disease or IgA nephropathy).

METHODS

In each of the enrolled 46 patients with CKD stage 3 or 4, serum creatinine concentration was assessed, eGFR (MDRD) was calculated, also central blood pressure and pulse wave velocity (PWV) was assessed and the 24-hour ambulatory blood pressure monitoring (ABPM) was conducted at the beginning of the study and then repeated after one-year observation period.

RESULTS

During the observation period mean eGFR decreased from 44.1 (33.2-50.6) mL/min to 36.7 (29.7-46.3) mL/min. No significant differences were observed in the peripheral blood pressure or central blood pressure parameters. After one-year observation period the values of diastolic blood pressure dipping during the night significantly decreased from 16 (13-19) mmHg to 12 (10-15) mmHg; p< 0.05. The values of systolic dipping during the night or the mean BP values recorded in ABPM did not change significantly. Additionally, no significant differences in the PWV values were found. In the multivariate regression model the change of serum creatinine concentration was explained by the initial diastolic dipping values.

CONCLUSION

1. In patients with CKD stages 3 or 4 and mild or no- proteinuria, peripheral and central blood pressure did not change significantly during a one-year observation period despite the significant decline of eGFR and seems not to participate in the CKD progression. 2. Reduced magnitude of the diastolic dipping, which reflects the increase of diastolic blood pressure load during the nighttime, may play an important role in the pathogenesis of deterioration of kidney function in these patients.

Altered Circadian Timing System-Mediated Non-Dipping Pattern of Blood Pressure and Associated Cardiovascular Disorders in Metabolic and Kidney Diseases

The morning surge in blood pressure (BP) coincides with increased cardiovascular (CV) events. This strongly suggests that an altered circadian rhythm of BP plays a crucial role in the development of CV disease (CVD). A disrupted circadian rhythm of BP, such as the non-dipping type of hypertension (i.e., absence of nocturnal BP decline), is frequently observed in metabolic disorders and chronic kidney disease (CKD). The circadian timing system, controlled by the central clock in the suprachiasmatic nucleus of the hypothalamus and/or by peripheral clocks in the heart, vasculature, and kidneys, modulates the 24 h oscillation of BP. However, little information is available regarding the molecular and cellular mechanisms of an altered circadian timing system-mediated disrupted dipping pattern of BP in metabolic disorders and CKD that can lead to the development of CV events. A more thorough understanding of this pathogenesis could provide novel therapeutic strategies for the management of CVD. This short review will address our and others' recent findings on the molecular mechanisms that may affect the dipping pattern of BP in metabolic dysfunction and kidney disease and its association with CV disorders.

Seasonal proteinuria changes in IgA nephropathy patients after proteinuria remission

Background

Proteinuria is a powerful prognostic factor for end-stage renal disease in IgA nephropathy (IgAN) patients. However, it is not known whether proteinuria exacerbations are related to seasonal changes.

Methods

We retrospectively enrolled consecutive patients diagnosed with IgAN by kidney biopsy at our hospital between 2002 and 2014. Proteinuria remission was defined as urinary protein <0.3 g/gCr in two consecutive outpatient urinalyses and exacerbation as urinary protein ≥0.75 g/gCr. Four seasons were defined: spring (March–May), summer (June–August), autumn (September–November), and winter (December–February). We performed a multivariate analysis to identify factors associated with the second remission following a proteinuria exacerbation.

Results

We analyzed 116 patients. Proteinuria remission and exacerbation occurred in 77, and 43 patients, respectively. The incidence of proteinuria exacerbation was significantly higher in autumn and winter than in spring and summer (p = 0.040). The cumulative second remission rate was significantly higher in patients with autumn and winter proteinuria exacerbation than in patients with spring and summer exacerbations (p = 0.0091). In multivariate analyses, exacerbation onset in autumn and winter (hazard ratio [HR], 3.51; 95% confidence interval [CI], 1.41–8.74) and intensive therapy (HR, 2.26; 95% CI, 1.05–4.88) were significantly associated with a second proteinuria remission.

Conclusion

In IgAN patients in proteinuria remission, proteinuria exacerbation frequently occurred in autumn and winter. Exacerbations occurring in autumn and winter tended to remit early.