Chronic Kidney Disease: The Silent Epidemy

The role of PI3K/Akt signaling pathway in chronic kidney disease

Chronic kidney disease (CKD), including chronic glomerulonephritis, IgA nephropathy and diabetic nephropathy, are common chronic diseases characterized by structural damage and functional decline of the kidneys. The current treatment of CKD is symptom relief. Several studies have reported that the phosphatidylinositol 3 kinases (PI3K)/protein kinase B (Akt) signaling pathway is a pathway closely related to the pathological process of CKD. It can ameliorate kidney damage by inhibiting this signal pathway which is involved with inflammation, oxidative stress, cell apoptosis, epithelial mesenchymal transformation (EMT) and autophagy. This review highlights the role of activating or inhibiting the PI3K/Akt signaling pathway in CKD-induced inflammatory response, apoptosis, autophagy and EMT. We also summarize the latest evidence on treating CKD by targeting the PI3K/Akt pathway, discuss the shortcomings and deficiencies of PI3K/Akt research in the field of CKD, and identify potential challenges in developing these clinical therapeutic CKD strategies, and provide appropriate solutions.

Glycosylation Analysis of Urinary Peptidome Highlights IGF2 Glycopeptides in Association with CKD

Chronic kidney disease (CKD) is prevalent in 10% of world’s adult population. The role of protein glycosylation in causal mechanisms of CKD progression is largely unknown. The aim of this study was to identify urinary O-linked glycopeptides in association to CKD for better characterization of CKD molecular manifestations. Urine samples from eight CKD and two healthy subjects were analyzed by CE-MS/MS and glycopeptides were identified by a specific software followed by manual inspection of the spectra. Distribution of the identified glycopeptides and their correlation with Age, eGFR and Albuminuria were evaluated in 3810 existing datasets. In total, 17 O-linked glycopeptides from 7 different proteins were identified, derived primarily from Insulin-like growth factor-II (IGF2). Glycosylation occurred at the surface exposed IGF2 Threonine 96 position. Three glycopeptides (DVStPPTVLPDNFPRYPVGKF, DVStPPTVLPDNFPRYPVG and DVStPPTVLPDNFPRYP) exhibited positive correlation with Age. The IGF2 glycopeptide (tPPTVLPDNFPRYP) showed a strong negative association with eGFR. These results suggest that with aging and deteriorating kidney function, alterations in IGF2 proteoforms take place, which may reflect changes in mature IGF2 protein. Further experiments corroborated this hypothesis as IGF2 increased plasma levels were observed in CKD patients. Protease predictions, considering also available transcriptomics data, suggest activation of cathepsin S with CKD, meriting further investigation.

Nomogram model for predicting early onset of chronic kidney disease using color Doppler region of interest technique

PURPOSE

The risk factors of chronic kidney disease were analyzed by using the region of interest quantitative technology of color Doppler combined with QLab software, and a Nomogram was established to conduct an individualized assessment of patients with chronic kidney disease.

METHODS

A total of 500 patients with chronic kidney disease diagnosed in our hospital from June 2019 to March 2021 were selected as the chronic kidney disease group, and 300 healthy patients during the same period were selected as the control group. Univariate analysis was performed on the test indexes and the vascularity index, flow index, and vascularization flow index measured by the color doppler region of interest quantitative technique. The above meaningful indicators were included in the Logistics regression analysis to obtain the independent risk factors of early chronic kidney disease. The independent risk factors were imported into R software to draw a Nomogram model for predicting early chronic kidney disease and evaluate the model.

RESULTS

Single factor analysis results suggest age, hypertension, diabetes, hyperlipidemia, disease of heart head blood-vessel, body mass index, vascularity index, flow index, and vascularization flow index, fasting blood sugar, triglyceride, total cholesterol, urea nitrogen, creatinine, uric acid, glomerular filtration rate differences statistically significant (P < 0.05). Logistics regression analysis showed that hypertension, diabetes, flow index, and vascularization flow index, urea nitrogen, and albumin were independent risk factors for the early occurrence of chronic kidney disease. The C-index of this Nomogram using independent risk factors is 0.896 (95%CI 0.862-0.930), which indicates that the Nomogram has good discriminant power. The receiver operating curve of the histograph was area under the curve (AUC) 0.884 (95%CI 0.860-0.908). The receiver operator characteristic curve (ROC) of urea nitrogen, albumin, flow index, and vascularization flow index were evaluated. The results indicated that the best cutoff value of urea nitrogen was 5.9 mmol/L, flow index was 14.67, vascularization flow index was 4.6, and albumin was 40.26 g/L.

CONCLUSION

In the prediction of chronic kidney disease I-II stage, the quantitative technique of color Doppler region of interest has certain diagnostic value. The model established in this study has good discriminative power and can be applied to clinical practice, giving certain indicative significance.

Efficacy and Safety of Salvia miltiorrhiza for Treating Chronic Kidney Diseases: A Systematic Review and Meta-Analysis

Objective

This meta-analysis evaluated the effects and potential harms of Salvia miltiorrhiza or its extracts Salvianolate and Tanshinone for the treatment of population with a chronic kidney disease (CKD).

Methods

We searched for the randomized clinical trials (RCTs) through databases including the Cochrane Library, PubMed, Embase, Web of Science, Current Controlled Trials, China National Knowledge Infrastructure (CNKI), Wanfang Data Knowledge Service Platform (Wanfang Data), China Biology Medicine Disc (SinoMed), and Chinese Clinical Trial Registry (ChiCTR). Meta-analysis was performed with STATA 16 software after data extraction. The risk of bias was assessed with the Cochrane risk-of-bias tool (RoB 2.0), and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework was employed to evaluate the quality of evidence.

Result

A total of 32 studies were included involving 2264 participants. Compared to the control group, the treatment group significantly decreased serum creatinine (SCr) (SMD −0.60, 95% CI −0.79 to −0.41, P < 0.0001), blood urea nitrogen (BUN) (SMD −0.66, 95% CI −0.81 to −0.50, P < 0.0001), Cystatin C (CysC) (SMD −5.16, 95% CI −14.84 to 4.53, P=0.297), 24 hour urine protein (24 h UPE) (SMD −0.70, 95% CI −1.21 to −0.19, P=0.008), time to initiation of dialysis (Log RR 0.43, 95% CI 0.23 to 0.81, P=0.0089), serum total cholesterol (TC) (SMD −0.53, 95% CI −0.88 to −0.17, P=0.0042, P=0.0035), plasma fibrinogen (FIB) (SMD −0.79, 95% CI −1.12 to −0.46, P < 0.0001), C-reactive protein (CRP) (SMD −0.56, 95% CI −0.93 to −0.19, P=0.0029); increased creatinine clearance (Ccr) (SMD 0.92, 95% CI 0.43 to 1.41, P=0.0002), glomerular filtration rate (GFR) (SMD 0.56, 95% CI 0.30 to 0.83, P < 0.001), effective rate (Log RR 0.30, 95% CI 0.23 to 0.37, P < 0.0001), and hemoglobin (Hb) (SMD 0.42, 95% CI 0.13 to 0.71, P=0.0042). Moreover, the incidences of adverse effects were similar between the two groups.

Conclusions

Salvia miltiorrhiza or its extracts Salvianolate and Tanshinone, as a complementary therapy to conventional medicine, presents potential impacts to improve kidney functions and delay the progression of CKD without obvious adverse effects. However, the certainty of the evidence and the risk of bias are suboptimal and further clinical studies are still required to determine the underlying effects.

Hemostasis and oxidative stress in chronic kidney disease in children and adolescents

Chronic kidney disease (CKD) can be defined as the progressive loss of renal function, characterized by decreased glomerular filtration rate (GFR). The etiology of CKD in childhood is mainly associated with congenital anomalies of the kidneys and urinary tract (CAKUT) and to glomerular diseases. The goal of this study was to investigate the hemostasis and oxidative stress in pediatric CKD of different etiologies. 54 CKD children and adolescents and 52 controls were enrolled in this study. The evaluation of hemostasis was carried out by determination of D-Dimer (D-Di) and plasminogen activator inhibitor (PAI-1) plasma levels, while oxidative stress by thiobarbituric acid reactive substances (TBARS) levels, protein carbonyl content, plasma antioxidant capacity (MTT) and ascorbate. The D-Di was increased in CAKUT stage 3 or 4 patients compared to those with glomerular disease. PAI-1 was increased in patients with glomerular disease compared to CAKUT. Carbonyl protein content was higher in the control group compared to glomerular disease stage 3 or 4 patients. Our findings showed that the reduction in GFR is associated with a state of hypercoagulability. The analysis of integrated networks showed an expansion of connections among hemostatic and oxidative stress markers in CKD children and adolescents comparing to controls.

Steatosis is involved in the progression of kidney disease in a high-fat-diet-induced non-alcoholic steatohepatitis mouse model

Chronic kidney disease (CKD) and non-alcoholic steatohepatitis (NASH) are major health issues associated with the metabolic syndrome. Although NASH is a known risk factor of CKD, the mechanisms linking these two diseases remain poorly understood. We aimed to investigate alterations in the kidney complicated with dyslipidemia in an established NASH mouse model. Male C57BL6/J mice were fed with control diet or high-fat diet (HFD), containing 40% fat, 22% fructose, and 2% cholesterol for 16 weeks. Metabolic characteristics, histological changes in the kidney, endoplasmic reticulum (ER) stress, apoptosis, and fibrosis were evaluated by histological analysis, immunoblotting, and quantitative reverse transcription-polymerase chain reaction. Levels of serum aspartate aminotransferase, alanine aminotransferase, alkali-phosphatase, total cholesterol, and urinary albumin were significantly higher in mice fed with HFD. Remarkable steatosis, glomerular hypertrophy, and interstitial fibrosis were also shown in in the kidney by leveraging HFD. Furthermore, HFD increased the mRNA expression levels of Casp3, Tgfb1, and Nfe2l2 and the protein level of BiP. We observed the early changes of CKD and speculate that the underlying mechanisms that link CKD and NASH are the induction of ER stress and apoptosis. Further, we observed the activation of Nfe2l2 in the steatosis-induced CKD mouse model. This NASH model holds implications in investigating the mechanisms linking dyslipidemia and CKD.

Obesity Management and Chronic Kidney Disease

Obesity is one of the risk factors for the development and progression of chronic kidney disease (CKD). Several studies have shown the association between increased body mass index and kidney function decline. Obesity leads to CKD directly by acting as an independent risk factor and indirectly through increasing risks for diabetes, hypertension, and atherosclerosis, a group of well-established independent risk factors for CKD. Alterations in renal hemodynamics, inflammation, and in hormones and growth factors results in hyperfiltration injury and focal segmental glomerulosclerosis. In recent years, many studies have shown that the gut microbiome may play a role in the pathogenesis of obesity. Dysbiosis has been noted in obese subjects in both human and animal studies. Changes in the gut microbiome in obese patients promote weight gain by effectively extracting energy from diet, and induction of low-grade inflammation. Evidence also points to the role of inflammation within the adipose tissue in obesity as a key factor in the pathogenesis of obesity-related complications. Thus, obesity is the net result of complex interactions between behavioral, genetic, and environmental factors. In terms of management, conservative approaches are often the first option, but they often are unsuccessful in achieving and/or maintaining weight loss, particularly in severe obesity. Consequently, nonmedical management with bariatric surgery is the most effective treatment option for morbid obesity and has shown mitigation of multiple risk factors for the progression of CKD. The most frequently performed interventions are vertical sleeve gastrectomy and Roux-en-Y gastric bypass. Studies have shown that bariatric surgery is associated with beneficial effects on CKD by mitigating its risk factors by weight loss, reducing insulin resistance, hemoglobin A1c, and proteinuria, in addition to positive long-term outcomes. Because of the epidemic of obesity, the prevalence of obesity in kidney transplant recipients also is increasing. The maximal body mass index (BMI) threshold for kidney transplantation is not clear. The Organ Procurement Transplant Network/Scientific Registry of Transplant Recipients 2019 annual data report showed that the proportion of kidney transplant recipient candidates with a BMI of 30 kg/m² or greater is increasing steadily. Morbid obesity is linked to adverse graft outcomes including delayed graft function, primary nonfunction, and decreased graft survival. Obesity is also an independent risk factor for cardiovascular death in kidney transplant recipients, suggesting that these patients should not be excluded from transplantation based on their BMI because transplantation is associated with lower mortality compared with dialysis. However, many centers exclude obese patients (with different BMI cut-off values) from transplantation to avoid postoperative complications. To minimize the surgical complications of kidney transplantation in obese patients, our center has adopted the robot-assisted kidney transplantation procedure. Our data show that this approach is comparable with historical nonobese controls in the United Network for Organ Sharing database in terms of patient and graft survival. Another surgical option for this group of patients at our center is a combined robotic sleeve gastrectomy and robotic-assisted kidney transplant. In a recent study, this approach showed promising results in terms of weight loss, patient survival, and graft survival, and might become more common in the future.

Short-term exposure to fine particulate air pollution and emergency department visits for kidney diseases in the Atlanta metropolitan area

Toxicological evidence has shown that fine particulate matter (PM_2.5) may affect distant organs, including kidneys, over the short term. However, epidemiological evidence is limited.

OBJECTIVES

We investigated associations between short-term exposure to PM_2.5, major PM_2.5 components [elemental carbon (EC), organic carbon (OC), sulfate, and nitrate], and gaseous co-pollutants (O₃, CO, SO₂, NO₂, and NO_x) and emergency department (ED) visits for kidney diseases during 2002-2008 in Atlanta, Georgia.

METHODS

Log-linear time-series models were fitted to estimate the acute effects of air pollution, with single-day and unconstrained distributed lags, on rates of ED visits for kidney diseases [all renal diseases and acute renal failure (ARF)], controlling for meteorology (maximum air and dew-point temperatures) and time (season, day of week, holidays, and long-term time trend).

RESULTS

For all renal diseases, we observed positive associations for most air pollutants, particularly 8-day cumulative exposure to OC [rate ratio (RR) = 1.018, (95% confidence interval [CI]: 1.003, 1.034)] and EC [1.016 (1.000, 1.031)] per interquartile range increase exposure. For ARF, we observed positive associations particularly for 8-day exposure to OC [1.034 (1.005, 1.064)], EC [1.032 (1.002, 1.063)], nitrate [1.032 (0.996, 1.069)], and PM_2.5 [1.026 (0.997, 1.057)] per interquartile range increase exposure. We also observed positive associations for most criteria gases. The RR estimates were generally higher for ARF than all renal diseases.

CONCLUSIONS

We observed positive associations between short-term exposure to fine particulate air pollution and kidney disease outcomes. This study adds to the growing epidemiological evidence that fine particles may impact distant organs (e.g., kidneys) over the short term.

Changes of protein levels in human urine reflect the dysregulation of signaling pathways of chronic kidney disease and its complications

The increasing prevalence of chronic kidney disease (CKD) seriously is threatening human health and overall quality of life. The discovery of biomarkers of pathogenesis of CKD and the associated complications are very important for CDK diagnosis and treatment. In this paper, urine protein biomarkers were investigated because urine sample collection is convenient and non-invasive. We analyzed the protein concentrations in the urine of CKD patients and extracted abnormal protein signals comparing with the healthy control groups. The enriched signaling pathways that may characterize CKD pathology were identified from these proteins. We applied surface-enhanced laser desorption and ionization time of flight mass spectrometry technology to detect different protein peaks in urine samples from patients with CKD and healthy controls. We searched the proteins corresponding to protein peaks through the UniProt database and identified the signaling pathways of CKD and its complications by using the NIH DAVID database. 42 low abundance proteins and 46 high abundance proteins in the urine samples from CKD patients were found by comparing with healthy controls. Seven KEGG pathways related to CKD and its complications were identified from the regulated proteins. These pathways included chemokine signaling pathway, cytokine-cytokine receptor interaction, oxidative phosphorylation, cardiac muscle contraction, Alzheimer's disease, Parkinson's disease, and salivary secretion. In CKD stages 2, 3, 4, and 5, five proteins showed significantly differential abundances. The differential protein signals and regulated signaling pathways will provide new insight for the pathogenesis of CKD and its complications. These altered proteins may also be used as novel biomarkers for the noninvasive and convenient diagnosis methods of CKD and its complications through urine testing in the future.

Chronic Kidney Disease and Its Impact on a Prothrombotic State in Patients with Atrial Fibrillation

It is unclear whether chronic kidney disease (CKD) increases thromboembolism in atrial fibrillation (AF). We conducted a retrospective cross-sectional analysis of 502 non-anticoagulated AF patients (median age, 66 (60–73) years, median CHA₂DS₂-VASc score, 3.0 (2.0–4.0)) with an estimated glomerular filtration rate (eGFR) ≥ 15 mL/min/1.73 m². Endogenous thrombin potential (ETP), clot permeability (K_s), and clot lysis time (CLT), among others, were determined. Patients with stage 4 CKD (n = 87; 17.3%) had higher ETP and prolonged CLT compared with those with stage 3 CKD. In patients with stages 3 to 4 CKD (n = 180; 35.9%) N-terminal pro-B-type natriuretic peptide predicted low K_s (the lowest quartile, odds ratio [OR] per 100 pg/mL: 1.03, 95% confidence interval [CI]: 1.01–1.06) and prolonged CLT (the top quartile, OR per 100 pg/mL: 1.05, 95% CI: 1.02–1.08), but not high ETP. In the whole cohort, after adjustment for CHA₂DS₂-VASc score, stage 4 CKD, but not stage 3 CKD, predicted high ETP (OR: 9.06; 95% CI: 4.44−18.46) and prolonged CLT (OR: 3.58; 95% CI: 1.76–7.28), but not low K_s. compared to the reference eGFR category. This study is the first to demonstrate the prothrombotic and antifibrinolytic alterations in AF patients with stage 4 CKD, but not stage 3 CKD irrespective of clinical stroke risk factors.