Cystatin C: a kidney function biomarker

Lower serum creatinine to cystatin C ratio associated with increased incidence of frailty in community-dwelling elderly men but not in elderly women

BACKGROUND

Sarcopenia has been reported to play an important role in frailty syndrome. The serum creatinine/serum cystatin C ratio (Scr/Cys C ratio) has recently been recognized as a valuable indicator for assessing sarcopenia. However, few studies have examined the association between serum creatinine/serum cystatin C ratio and frailty. The objective of this study is to investigate the relationship between the serum creatinine/serum cystatin C ratio and frailty among older adults residing in the community.

METHODS AND MATERIALS

A Total of 1926 community-dwelling older adults aged ≥ 60 years in the 2011 waves of the China Health and Retirement Longitudinal Study (CHARLS) were included. The participants' frailty status was determined using a 39 item frailty index (FI), which classified individuals as "robust" (FI ≤ 0.1), "pre-frailty" (0.1 < FI < 0.25), or "frailty" (FI ≥ 0.25). The Scr/Cys C ratio was determined by dividing the serum creatinine level (mg/dL) by the cystatin C level (mg/L). The one-way analysis of variance(ANOVA) and Chi-squared test (χ2)were applied to compare the differences between the 3 groups. Both linear regression and logistic regression models were used to further investigate the relationship between Scr/Cys C ratio and frailty.

RESULTS

After adjusting for potential confounding factors, the study revealed that participants in the Q1 quartile of Scr/Cys C ratio had increased odds of frailty (Q1vs.Q4: OR = 1.880, 95% CI 1.126-3.139, p = 0.016) compared with those in the Q4 quartile group. In fully adjusted logistic regression models, male participants in the Q2 quartile of Scr/Cys C ratio were significantly correlated with higher odds of pre-frailty (Q2 vs.Q4: OR = 1.693, 95%CI 1.040-2.758, p = 0.034). However, this correlation was not observed in females (OR = 0.984, 95% CI 0.589-1.642, p = 0.950,). Additionally, the study observed an increase in both the frailty index and the incidence of frailty as age increased in both males and females.

CONCLUSION

Among community-dwelling older adults, lower Serum creatinine to cystatin C ratio were found to be associated with increased odds of frailty prevalence in males.

The clinical significance and prognostic value of serum beta-2 microglobulin in adult lymphoma-associated hemophagocytic lymphohistiocytosis: a multicenter analysis of 326 patients

To investigate the prognostic impact of serum beta-2 microglobulin (B2M) in adult lymphoma-associated hemophagocytic lymphohistiocytosis (HLH). The clinical and laboratory characteristics of 326 adult patients in a multicenter cohort with lymphoma-associated HLH with available baseline serum B2M levels were retrospectively analyzed. A total of 326 cases were included in this study, and the median serum B2M level was 5.19 mg/L. The optimal cut-off of serum B2M was 8.73 mg/L, and the cases with serum B2M level >8.73 mg/L were older and had a more advanced stage, lower levels of platelets, albumin, and fibrinogen, and higher creatinine level. The serum B2M >8.73 mg/L, creatinine ≥133 μmol/L, fibrinogen ≤1.5 g/L, agranulocytosis (<0.5 × 109/L), severe thrombocytopenia (<50 × 109/L), and high Epstein-Barr virus DNA copy number were found to have independent prognostic values in all patients, and the serum B2M >8.73 mg/L was also an independent prognostic factor in patients with creatinine <133 μmol/L. Finally, a prognostic scoring system was established based on independent prognostic factors of all patients and categorized the patients into three groups with significant prognostic differences. This study confirmed that the serum B2M level can be an independent prognostic factor in lymphoma-associated HLH and established a prognostic scoring system to predict patients' survival.

Acute kidney injury after intracerebral hemorrhage: a mini review

Intracerebral hemorrhage (ICH) stands as a prevalent and pivotal clinical condition. The potential cooccurrence of acute kidney injury (AKI) among afflicted individuals can profoundly influence their prognosis. In recent times, there has been a growing focus among clinical practitioners on researching the relationship between ICH and AKI. AKI occurring concurrently with ICH predominantly arises from both hemodynamic and non-hemodynamic mechanisms. The latter encompasses neurohumoral regulation, inflammatory response, oxidative stress, and iatrogenic factors such as contrast agents, dehydrating agents, antibiotics, and diuretics. Moreover, advanced age, hypertension, elevated baseline creatinine levels, chronic kidney disease, and larger hematomas predispose patients to AKI. Additionally, the current utilization of biomarkers and the development of predictive models appear promising in identifying patients at risk of AKI after ICH. This article aims to underscore the potential of the aforementioned insights to inspire novel approaches to early clinical intervention.

VEGF-induced Nrdp1 deficiency in vascular endothelial cells promotes cancer metastasis by degrading vascular basement membrane

Vascular endothelial cells (VECs) are key players in the formation of neovessels and tumor metastasis, the ultimate cause of the majority of cancer-related human death. However, the crosstalk between VECs and metastasis remain greatly elusive. Based on our finding that tumor-associated VECs present significant decrease of Nrdp1 protein which is closely correlated with higher metastatic probability, herein we show that the conditional medium from hypoxia-incubated cancer cells induces extensive Nrdp1 downregulation in human and mouse VECs by vascular endothelial growth factor (VEGF), which activates CHIP, followed by Nrdp1 degradation in ubiquitin-proteasome-dependent way. More importantly, lung metastases of cancer cells significantly increase in conditional VECs Nrdp1 knockout mice. Mechanically, Nrdp1 promotes degradation of Fam20C, a secretory kinase involved in phosphorylating numerous secreted proteins. Reciprocally, deficiency of Nrdp1 in VECs (ecNrdp1) results in increased secretion of Fam20C, which induces degradation of extracellular matrix and disrupts integrity of vascular basement membrane, thus driving tumor metastatic dissemination. In addition, specific overexpression of ecNrdp1 by Nrdp1-carrying adeno-associated virus or chemical Nrdp1 activator ABPN efficiently mitigates tumor metastasis in mice. Collectively, we explore a new mechanism for VEGF to enhance metastasis and role of Nrdp1 in maintaining the integrity of vascular endothelium, suggesting that ecNrdp1-mediated signaling pathways might become potential target for anti-metastatic therapies.

A link between circulating immune complexes and acute kidney injury in human visceral leishmaniasis

Visceral leishmaniasis (VL) is an infectious disease caused by Leishmania infantum. Clinically, VL evolves with systemic impairment, immunosuppression and hyperactivation with hypergammaglobulinemia. Although renal involvement has been recognized, a dearth of understanding about the underlying mechanisms driving acute kidney injury (AKI) in VL remains. We aimed to evaluate the involvement of immunoglobulins (Igs) and immune complexes (CIC) in the occurrence of AKI in VL patients. Fourteen VL patients were evaluated between early treatment and 12 months post-treatment (mpt). Anti-Leishmania Igs, CIC, cystatin C, C3a and C5a were assessed and correlated with AKI markers. Interestingly, high levels of CIC were observed in VL patients up to 6 mpt. Concomitantly, twelve patients met the criteria for AKI, while high levels of cystatin C were observed up to 6 mpt. Plasmatic cystatin C was positively correlated with CIC and Igs. Moreover, C5a was correlated with cystatin C, CIC and Igs. We did not identify any correlation between amphotericin B use and kidney function markers in VL patients, although this association needs to be further explored in subsequent studies. Our data reinforce the presence of an important renal function impairment during VL, suggesting the involvement of Igs, CIC, and C5a in this clinical condition.

Creatinine-to-cystatin C ratio and body composition predict response to PD-1 inhibitors-based combination treatment in metastatic gastric cancer

Background

Creatinine-to-cystatin C ratio (CCR) and body composition (BC) parameters have emerged as significant prognostic factors in cancer patients. However, the potential effects of CCR in gastric cancer (GC) remains to be elucidated. This multi-center retrospective study explored the predictive and prognostic value of CCR and BC-parameters in patients with metastatic GC receiving PD-1 inhibitors-based combination therapy.

Methods

One hundred and thirteen GC patients undergoing PD-1 inhibitors-based combination therapy were enrolled at three academic medical centers from January 2021 to July 2023. A deep-learning platform based on U-Net was developed to automatically segment skeletal muscle index (SMI), subcutaneous adipose tissue index (SATI) and visceral adipose tissue index (VATI). Patients were divided into two groups based on the median of CCR or the upper tertile of BC-parameters. Logistic and Cox regression analysis were used to determine the effect of CCR and BC-parameters in predicting response rates and survival rates.

Results

The CCR was positively correlated with SMI (r=0.43; P<0.001), but not with SATI or VATI (P>0.05). Multivariable logistic analysis identified that both low CCR (OR=0.423, P=0.066 for ORR; OR=0.026, P=0.005 for DCR) and low SATI (OR=0.270, P=0.020 for ORR; OR=0.149, P=0.056 for DCR) were independently associated with worse objective response rate (ORR) and disease control rate (DCR). Patients with low CCR or low SATI had significantly lower 8-month progression-free survival (PFS) rate and 16-month overall survival (OS) rate than those with high CCR (PFS rate, 37.6% vs. 55.1%, P=0.011; OS rate, 19.4% vs. 44.9%, P=0.002) or those with high SATI (PFS rate, 37.2% vs. 53.8%, P=0.035; OS rate, 8.0% vs. 36.0%, P<0.001). Multivariate Cox analysis showed that low CCR (HR=2.395, 95% CI: 1.234-4.648, P=0.010 for PFS rate; HR=2.528, 95% CI: 1.317-4.854, P=0.005 for OS rate) and low SATI (HR=2.188, 95% CI: 1.050-4.560, P=0.037 for PFS rate; HR=2.818, 95% CI: 1.381-5.752, P=0.004 for OS rate) were both independent prognostic factors of poor 8-month PFS rate and 16-month OS rate. A nomogram based on CCR and BC-parameters showed a good performance in predicting the 12- and 16-month OS, with a concordance index of 0.756 (95% CI, 0.722-0.789).

Conclusions

Low pre-treatment CCR and SATI were independently associated with lower response rates and worse survival in patients with metastatic GC receiving PD-1 inhibitors-based combination therapy.

Estimated glomerular filtration rate in clinical practice: Consensus positioning of the Brazilian Society of Nephrology (SBN) and Brazilian Society of Clinical Pathology and Laboratory Medicine (SBPC/ML)

Chronic kidney disease (CKD) represents one of today's main public health problems. Serum creatinine measurement and estimation of the glomerular filtration rate (GFR) are the main tools for evaluating renal function. There are several equations to estimate GFR, and CKD-EPI equation (Chronic Kidney Disease - Epidemiology) is the most recommended one. There are still some controversies regarding serum creatinine measurement and GFR estimation, since several factors can interfere in this process. An important recent change was the removal of the correction for race from the equations for estimating GFR, which overestimated kidney function, and consequently delayed the implementation of treatments such as dialysis and kidney transplantation. In this consensus document from the Brazilian Societies of Nephrology and Clinical Pathology and Laboratory Medicine, the main concepts related to the assessment of renal function are reviewed, as well as possible existing controversies and recommendations for estimating GFR in clinical practice.

Mediterranean diet and a health behavior index in relation to cardiovascular biomarkers: Data from the Health and Retirement Study

BACKGROUND AND AIM

Although lifestyle factors have been repeatedly examined for their role on cardiovascular diseases, their composite effect has not been frequently explored. We aimed to investigate the relation of dietary patterns (DPs) and a health behavior index (HBI) with cardiovascular biomarkers.

METHODS AND RESULTS

A cross-sectional analysis with data from 3461 US residents, participants in the Health and Retirement Study (HRS), was performed. Nutritional data were obtained with a food frequency questionnaire, while adherence to Mediterranean Diet (MD) was determined by the Mediterranean Diet Score. A posteriori DPs were estimated using principal component analysis and the HBI was constructed combining adherence to MD, smoking status, physical activity levels, alcohol consumption and body mass index. Multiple linear regression models were performed to examine the relation between DPs or HBI and levels of C-reactive protein (CRP), glycosylated hemoglobin (HbA1C), cystatin C (Cys C), total cholesterol (TC), high density lipoprotein (HDL) and TC:HDL in blood. Multiple linear regression showed that the "healthy" DP and the MD had a significant negative association with CRP and Cys C (p < 0.05), while the "Western-type" DP had a significant positive association with TC:HDL ratio, CRP and Cys C. Moreover, the HBI was positively associated with HDL (p < 0.05) and negatively associated with TC:HDL ratio, CRP and Cys C (p < 0.05).

CONCLUSIONS

Adherence to MD and to a healthy dietary pattern was negatively associated with biomarkers of inflammation, while the HBI was associated with a better cardiometabolic profile, assessed with blood biomarkers.

Phospholipid-functionalized gold electrode for cellular membrane interface studies - interactions between DMPC bilayer and human cystatin C

This work describes the electrochemical studies on the interactions between V57G mutant of human cystatin C (hCC V57G) and membrane bilayer immobilized on the surface of a gold electrode. The electrode was modified with 6-mercaptohexan-1-ol (MCH) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). DMPC was used as a membrane mimetic for monitoring electrochemical changes resulting from the interactions between the functionalized electrode surface and human cystatin C. The interactions between the modified electrode and hCC V57G were investigated by cyclic voltammetry and electrochemical impedance spectroscopy in a phosphate buffered saline (PBS) containing Fe(CN)63-/4- as a redox probe. The electrochemical measurements confirm that fabricated electrode is sensitive to hCC V57G at the concentration of 1 × 10-14 M. The incubation studies carried out at higher concentrations resulted in insignificant changes observed in cyclic voltammetry and electrochemical impedance spectroscopy measurements. The calculated values of surface coverage θR confirm that the electrode is equally covered at higher concentrations of hCC V57G. Measurements of wettability and surface free energy made it possible to determine the influence of individual structural elements of the modified gold electrode on its properties, and thus allowed to understand the nature of the interactions. Contact angle values confirmed the results obtained during electrochemical measurements, indicating the sensitivity of the electrode towards hCC V57G at the concentration of 1 × 10-14 M. In addition, the XPS spectra confirmed the successful anchoring of hCC V57G to the DMPC-functionalized surface.

Utilizing multimodal approach to identify candidate pathways and biomarkers and predicting frailty syndrome in individuals from UK Biobank

Frailty, a prevalent clinical syndrome in aging adults, is characterized by poor health outcomes, represented via a standardized frailty-phenotype (FP), and Frailty Index (FI). While the relevance of the syndrome is gaining awareness, much remains unclear about its underlying biology. Further elucidation of the genetic determinants and possible underlying mechanisms may help improve patients' outcomes allowing healthy aging.Genotype, clinical and demographic data of subjects (aged 60-73 years) from UK Biobank were utilized. FP was defined on Fried's criteria. FI was calculated using electronic-health-records. Genome-wide-association-studies (GWAS) were conducted and polygenic-risk-scores (PRS) were calculated for both FP and FI. Functional analysis provided interpretations of underlying biology. Finally, machine-learning (ML) models were trained using clinical, demographic and PRS towards identifying frail from non-frail individuals.Thirty-one loci were significantly associated with FI accounting for 12% heritability. Seventeen of those were known associations for body-mass-index, coronary diseases, cholesterol-levels, and longevity, while the rest were novel. Significant genes CDKN2B and APOE, previously implicated in aging, were reported to be enriched in lipoprotein-particle-remodeling. Linkage-disequilibrium-regression identified specific regulation in limbic-system, associated with long-term memory and cognitive-function. XGboost was established as the best performing ML model with area-under-curve as 85%, sensitivity and specificity as 0.75 and 0.8, respectively.This study provides novel insights into increased vulnerability and risk stratification of frailty syndrome via a multi-modal approach. The findings suggest frailty as a highly polygenic-trait, enriched in cholesterol-remodeling and metabolism and to be genetically associated with cognitive abilities. ML models utilizing FP and FI + PRS were established that identified frailty-syndrome patients with high accuracy.

Creatinine-cystatin C ratio and death with a functioning graft in kidney transplant recipients

Death with a functioning graft is important cause of graft loss after kidney transplantation. However, little is known about factors predicting death with a functioning graft among kidney transplant recipients. In this study, we evaluated the association between post-transplant creatinine-cystatin C ratio and death with a functioning graft in 1592 kidney transplant recipients. We divided the patients into tertiles based on sex-specific creatinine-cystatin C ratio. Among the 1592 recipients, 39.5% were female, and 86.1% underwent living-donor kidney transplantation. The cut-off value for the lowest creatinine-cystatin C ratio tertile was 0.86 in males and 0.73 in females. The lowest tertile had a significantly lower 5-year patient survival rate and was independently associated with death with a functioning graft (adjusted hazard ratio 2.574, 95% confidence interval 1.339-4.950, P < 0.001). Infection was the most common cause of death in the lowest tertile group, accounting for 62% of deaths. A low creatinine-cystatin C ratio was significantly associated with an increased risk of death with a functioning graft after kidney transplantation.

The Quantitative Detection of Cystatin-C in Patient Samples Using a Colorimetric Lateral Flow Immunoassay

A colloidal gold-based lateral flow immunoassay was developed for the rapid quantitative detection of Cystatin-C in serum and whole blood. This device has an assay time of 15 min, making it a convenient point-of-care diagnostic tool. The device has a quantification range spanning from 0.5 to 7.5 µg/mL, with a lower limit of detection at 0.18 µg/mL. To validate its accuracy, the test was compared to a standard nephelometric immunoassay, and the results exhibited a robust linear correlation with an adjusted r2 value of 0.95. Furthermore, the device demonstrates satisfactory levels of analytical performance in terms of precision, sensitivity, and interference, indicating its potential for precise Cystatin-C quantification, particularly in renal-failure patients. Notably, the Cystatin-C-LFA device also demonstrates satisfactory stability, as a 30-day accelerated stability study at 50 °C showed no change in the device performance, indicating a long shelf life for the product when stored at room temperature.

Combined detection of urinary biomarkers noninvasively predicts extent of renal injury in patients with early diabetic kidney disease with kidney qi deficiency syndrome: A retrospective investigation

Incipient diagnosis and noninvasive forecasts using urinary biomarkers are important for preventing diabetic kidney disease (DKD) progression, but they are also controversial. Previous studies have shown a potential relationship between urinary tubular biomarkers (UTBs) and traditional Chinese medicine (TCM) syndrome in patients with DKD. Thus, we further evaluated the clinical significance of combined detection of urinary biomarkers in noninvasively predicting the extent of renal damage in patients with early DKD with kidney qi deficiency syndrome, and preliminarily explored the potential biological link between UTBs and TCM syndrome in DKD. We categorized 92 patients with Type 2 diabetes mellitus into three groups as follows: 20 patients with normoalbuminuria, 50 patients with microalbuminuria, and 22 patients with macroalbuminuria. We found that, in all groups, 24 hr urinary albumin (24hUAlb) and urinary albumin-to-creatinine ratio (UACR) showed stepwise and significant increases. Urinary cystatin C (UCysC), urinary N-acetyl-β-d-glucosaminidase (UNAG), and urinary retinol-binding protein (URBP) synchronously increased gradually, consistent with the degree of albuminuria in all groups. Moreover, 24hUAlb and UACR were positively correlated with UCysC, UNAG, and URBP, respectively. In 72 patients with Type 2 DKD with albuminuria, a positive correlation was observed between UNAG and URBP, UCysC was also positively correlated with UNAG and URBP, respectively. Additionally, TCM syndrome distributional characteristics in all patients were consistent with clinical manifestations of kidney qi deficiency syndrome. Therefore, the combined detection of UCysC, UNAG, URBP, and UAlb may be used as a practical clinical technique to noninvasively forecast the extent of renal injury in patients with early Type 2 DKD with kidney qi deficiency syndrome. UTBs may be one of the biological bases of the specific TCM syndromes in DKD.

Current Status of Protein Biomarkers in Urolithiasis-A Review of the Recent Literature

Urolithiasis is an increasingly common clinical problem worldwide. The formation of stones is a combination of metabolic status, environmental factors, family history and many other aspects. It is important to find new ways to quickly detect and assess urolithiasis because it causes sudden, severe pain and often comes back. One way to do this is by exploring new biomarkers. Current advances in proteomic studies provide a great opportunity for breakthroughs in this field. This study focuses on protein biomarkers and their connection to kidney damage and inflammation during urolithiasis.

Biomarkers of Cardiovascular Diseases in Saliva and Gingival Crevicular Fluid: A Review

Due to the fact that cardiovascular diseases (CVDs) have become the most serious problem in public health, there is a need for new and efficient methods for screening and early detection. In the recent literature, saliva and gingival crevicular fluid (GCF) have been gaining recognition as sources of many potential biomarkers of various systemic diseases, mainly because of correlation between the level of some compounds in the blood and saliva and association between the composition of saliva and health status. In this review, we summarize published findings of patients with atherosclerosis, arterial hypertension, coronary artery disease (CAD), acute coronary syndrome (ACS), and stroke in the context of clinical utility of saliva and GCF in diagnosing and assessing CVD severity. We hypothesize that substances in saliva including inflammatory markers, enzymes, or hormones might become novel contributors to the diagnosis and screening of CVDs. In particular, C-reactive protein (CRP), tumor necrosis alpha (TNFα), and cortisol seem to be the most promising. However, further investigation is warranted to determine the most effective markers and methods for their analysis.

Sarcopenia and myosteatosis diagnostic tool for gastrointestinal cancer: creatinine to cystatin C ratio as evaluation marker

OBJECTIVE

This study aimed to develop a simplified diagnostic tool for assessing sarcopenia and myosteatosis in gastrointestinal cancer patients, focusing on the creatinine to cystatin C ratio (CCR) as an evaluation marker.

METHODS

955 patients were split into training (n = 671) and validation (n = 284) cohorts. Using logistic regression, risk factors for sarcopenia and myosteatosis were identified. The predictive capacity of the developed model was examined. The association between CCR and muscle imaging parameters, along with its impact on clinical outcomes, was analyzed.

RESULTS

No significant differences were observed in baseline traits between cohorts. CCR emerged as a significant risk factor for both sarcopenia and myosteatosis. Nomograms for diagnosing these conditions demonstrated strong predictive ability, with AUC values indicating high accuracy (sarcopenia AUC: 0.865-0.872; myosteatosis AUC: 0.848-0.849). The clinical utility of the nomograms was confirmed through decision curve analysis. CCR showed significant association with muscle imaging parameters and was a reliable indicator for assessing the risk of sarcopenia, myosteatosis, and cachexia. Moreover, CCR was able to differentiate between patient survival and disease progression rates.

CONCLUSION

A diagnostic tool for sarcopenia and myosteatosis in gastrointestinal cancer patients was developed, with CCR being a pivotal biomarker for disease diagnosis and prognosis prediction.

A magnetic solid phase chemiluminescent immunoassay for quantification of Cystatin C in human serum

A chemiluminescent immunoassay for human serum Cystatin C (Cys C) was established using a direct-antibody sandwich model. The immunoassay kit uses magnetic separation technology, using magnetic particles as the reaction solid phase, alkaline phosphatase as the marker enzyme, and a new chemiluminescent substrate APLS as the substrate. It has the characteristics of high sensitivity and short reaction time. This product uses high-affinity antibodies, resulting in a high specificity. The established method showed good accuracy, uniformity, and stability. The limit of detection was 2.39 ng/mL. The intra-assay coefficient of variation (CV) was 3.36%-6.00%, the interassay CV was 4.12%-5.35%, and the recovery rate was 99.07%. The correlation coefficient (r) of Cys-C kit was 0.999388 ≥ 0.9900. The accuracy of the developed method was tested by automatic chemiluminescence instrument (P > 0.05). The lowest titer was 0.92500, and the highest was 1.10000. The developed method showed a good correlation with the product from Roche by comparing these two kits in 240 clinical samples from China. In total, 1392 clinical patient from China samples were measured using the reagent kit developed in this study.

Therapeutic improvements of nifedipine controlled-release tablets combined with sacubitril valsartan on patients with diabetic nephropathy complicated with hypertension

This study aimed to evaluate the efficacy of nifedipine controlled-release tablets combined with sacubitril valsartan in diabetic nephropathy (DN) patients with hypertension. One hundred and twelve DN patients with hypertension were enrolled. They were randomly divided into the control group (treated with nifedipine controlled-release tablets combined with valsartan) and the observation group (treated with nifedipine controlled-release tablets combined with sacubitril valsartan). Renal function, endothelial function and inflammatory response were examined. After three-months treatment, the levels of clinical indexes (glycosylated hemoglobin, fasting blood glucose, systolic and diastolic blood pressure), renal function indicators (urinary albumin excretion rate, blood urea nitrogen, serum creatinine and cystatin C), endothelial function indicators (microalbumin, angiotensin II, thrombomodulin and cartilage oligomeric matrix protein) and inflammatory response factors (interleukin-6 and tumor necrosis factor-α) in the observation group were significantly lower than those in the control group. Nifedipine controlled-release tablets combined with sacubitril valsartan could effectively alleviate the progression of DN combined with hypertension.

Relationship of Frailty with Kidney Function in Adults More Than 60-Years-Old: Effect of Using Different Formulas to Estimate Glomerular Filtration Rate

Objective

Determine the relationship of renal function with frailty using different formulas for estimated glomerular filtration rate (eGFR).

Methods

Individuals who were 60-years-old or more (n=507) were recruited from August 2020 to June 2021, and the FRAIL scale was used to classify them as non-frail or frail. The three equations used to compute the eGFR were based on serum creatinine (eGFRcr), cystatin C (eGFRcys), or SCr+CysC (eGFRcr-cys). Renal function was classified using eGFR and defined as normal (≥90 mL/min/1.73m²), mild damage (59-89 mL/min/1.73m²), or moderate damage (≤60 mL/min/1.73m²). The relationship of frailty with renal function was analyzed. A subset of participants (n=358) was used to analyze changes in eGFR from 1 January 2012 to 31 December 2021 according to frailty and using the different eGFR equations.

Results

There were significant differences between the eGFRcr-cys and eGFRcr values in the frail group (P<0.05), but not the non-frail group; however, the differences between the eGFRcr-cys and eGFRcys values were significant in the frail and non-frail groups (P<0.001). Based on each eGFR equation, the prevalence of frailty increased as eGFR decreased (P<0.001), but there was no significant relationship after adjusting for age or the age-adjusted Charlson co-morbidity index. There were temporal declines in eGFR in all three frailty groups (robust, pre-frail, and frail), especially in the frail group (2.226 mL/min/1.73m² per year; P<0.001).

Conclusion

For older individuals who are frail, the eGFRcr value may not provide accurate estimates of renal function. Frailty is associated with a rapid decline in kidney function.

Lead exposure induced developmental nephrotoxicity in Japanese quail (Coturnix japonica) via oxidative stress-based PI3K/AKT pathway inhibition and NF-κB pathway activation

Birds are sensitive to environmental pollution and lead (Pb) contamination could negatively affect nearly all avian organs and systems including kidney of excretive system. Thereby, we used a biological model species-Japanese quail (Coturnix japonica) to examine the nephrotoxic effects of Pb exposure and possible toxic mechanism of Pb on birds. Quail chicks of 7-day-old were exposed to 50 ppm Pb of low dose and high dose of 500 ppm and 1000 ppm Pb in drinking water for five weeks. The results showed that Pb exposure induced kidney weight increase while body weight and length reduction. The increase of uric acid (UA), creatinine (CREA) and cystatin c (Cys C) in the plasma suggested renal dysfunction. Moreover, both microstructural and ultrastructural changes demonstrated obvious kidney damages. In particular, renal tubule epithelial cells and glomeruli swelling indicated renal inflammation. Furthermore, changes in the content and activity of oxidative stress markers suggested that Pb caused excessive oxidative stress in the kidney. Pb exposure also induced abnormal apoptosis in the kidney. In addition, RNA sequencing (RNA-Seq) analysis revealed that Pb disturbed molecular pathways and signaling related with renal function. Especially, Pb exposure resulted in an increase in renal uric acid synthesis by disrupting purine metabolism. Pb caused apoptotic increment by inhibiting the phosphatidylinositol-3-kinase (PI3K)/RAC-alpha serine/threonine-protein kinase (AKT) pathway and induced aggravated inflammation by activating Nuclear Factor kappa B (NF-κB) signaling pathway. The study implied that Pb caused nephrotoxicity through structural damages, uric acid metabolism disorder, oxidation imbalance, apoptosis and inflammatory pathway activation.

Comparison of Reversed-Phase and Mixed-Mode SPE for Enrichment and Clean-Up of Surrogate Peptides in CysC Quantified by LC-MS/MS

Accurate quantification of low-abundance protein Cystatin-C (CysC) in serum by liquid chromatography tandem mass spectrometry (LC-MS/MS) method is very difficult. After sample processing and tryptic digestion, the matrix of CysC surrogate peptides is very complexity, and the concentrations of them are very low, so solid-phase extraction (SPE) must be used to make the surrogate peptides purification and enrichment. In this paper, we used C18 reversed-phase SPE (RP-SPE) and mixed-mode SPE as SPE cartridges. We quantitatively assessed and compared the CysC surrogate peptides recoveries and matrix effects by different SPE cartridges. The sequence of CysC surrogate peptide is ALDFAVGEYNK, and sequence-specific subions y6 (VGEYNK+, m/z 709.3) and y9 (DFAVGEYNK+, m/z 1042.4) were selected for quantification of CysC, because the two fragment ions showed the highest sensitivity. In neat solution, the highest recoveries were similarly for y9 and y6 when used RP-SPE and mixed-mode SPE. However, in serum matrix, the recoveries were significantly higher when used mixed-mode SPE than RP-SPE, which was caused by matrix effects. Results showed that both RP-SPE and mixed-mode SPE were resulted in ion enhancement for CysC surrogate peptides quantification by LC-MS/MS, but mixed-mode SPE reduced more matrix effects. So mixed-mode SPE was more suitable SPE type for purification and enrichment of CysC surrogate peptides.

Estimated glomerular filtration rate with and without race for drug dosing: Cystatin C vs. serum creatinine

The goal of this study was to use a model kidney function clearance-dependent drug (vancomycin) to understand the gain or loss of precision in dosing with use of serum creatinine (S_cr ), serum cystatin C (S_cys ) and race and nonrace-based equations of the estimated glomerular filtration rate (eGFR). In this study of hospitalized patients, we compared S_cr , S_cys and their combination to estimate kidney function and vancomycin clearance. The nonrace-based S_cys eGFR model outperformed other clearance models and improved the probability of target attainment by 15%. When S_cys is not available, we show that the new 2021 CKD-EPI eGFR_cr equation (no race factor) performs as well as the current conventional approach. This improvement in model performance does not negate the need for individualized dosing but exemplifies the need to remove race as a factor of kidney-function dose adjustment.

Association between Serum Cys C and PTB Cavitation

Background

Cystatin C (Cys C) not only regulates the body's immune defenses but also contributes to tissue degradation and destruction by causing an imbalance between protease and antiprotease in infectious diseases. Is Cys C involved in pulmonary tuberculosis (PTB) infection and cavitation? We therefore conducted a retrospective study on this question to provide a basis for further studies.

Methods

Cavitary PTB patients, noncavitary PTB patients, and healthy controls were recruited in our study. Serum Cys C, CRP, BUN, UA, and CR were measured in all subjects, and the Kruskal-Wallis test was used to compare medians of these clinical parameters in different groups. The Spearman rank correlation test was used to determine correlations between variables. In addition, a multivariate analysis using binary logistic regression was used to identify factors associated with PTB cavitation.

Results

In our study, elevated serum Cys C levels were found in cavitary PTB patients compared to healthy controls and noncavitary patients (p = 0.022). Serum Cys C levels were statistically correlated with serum BUN and CR concentrations (r = 0.278, p = 0.005; r = 0.281, p = 0.004) in PTB patients. The binary logistic regression analysis showed that elevated serum Cys C levels were correlated with pulmonary cavitation in PTB patients (OR = 1.426, 95% CI: 1.071-1.898).

Conclusion

Elevated serum levels of Cys C are associated with pulmonary cavitation in PTB patients.

CST3 alleviates bilirubin-induced neurocytes' damage by promoting autophagy

High concentrations of unconjugated bilirubin (UCB) have toxic effects. The aim of our study was to find a way to elevate UCB tolerance or inhibit its toxicity in neurocytes. It has been reported that cystatin C (CST3) concentrations have a significant positive correlation with total bilirubin (TB) levels and a negative correlation with albumin levels. In addition, CST3 can directly bind UCB, decrease human umbilical vein endothelial cells' permeability, improve blood-brain barrier integrity after ischemic brain injury in mice, and induce autophagy. We hypothesized that CST3 could increase the solubility of UCB, decrease permeability of neurocytes, induce autophagy of neurocytes, and alleviate bilirubin-induced damage. To verify our hypothesis, we measured TB and conjugated bilirubin levels, and the permeability and autophagy of neurocytes treated with UCB and CST3. Our findings suggest that CST3 can protect against UCB-induced damage in neurocytes and that autophagy played an important role in this process.

Rivastigmine ameliorates gentamicin experimentally induced acute renal toxicity

The current experiment aimed to identify the possible protective role of rivastigmine (RIVA) in gentamicin (GNT)-induced acute kidney injury (AKI) in rats. RIVA was administered in the presence and absence of GNT. Kidney function markers and serum and renal GNT concentrations were measured. Renal oxidative stress parameters as well as inflammatory and apoptotic biomarkers were evaluated. Renal histopathological assessment and nuclear factor kappa-B (NF-κB) immunohistochemical study were performed. GNT administration increased serum creatinine, urea, and cystatin C concentrations. RIVA ameliorated these changes via mitigating GNT-induced increases of renal oxidative stress, inflammation, and apoptotic parameters. RIVA showed a prompt improvement in the histopathological renal damage and a decrease in NF-κB immunoexpression. In conclusion, RIVA protective effects against GNT-induced AKI are mediated by decreasing GNT concentration in renal tissue and other effects like antioxidant and antiapoptotic effects possibly through its cholinergic anti-inflammatory action.

Establishment of muscle mass-based indications for the cystatin C test in renal function evaluation

BACKGROUND

We aimed to suggest muscle mass-based criteria for using of the cystatin C test for the accurate estimated glomerular filtration rate (eGFR).

MATERIALS AND METHODS

We recruited 138 Korean subjects and evaluated eGFRcr (derived from Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) based on creatinine) was compared to eGFRcys based on cystatin C as the reference value. The skeletal muscle mass index (SMI) by bioelectrical impedance analysis (BIA) was used as representative of muscle mass. Calf circumference (CC) was also evaluated. We defined the patients by eGFRcr as those with values of eGFRcr ≥ 60 mL/min/1.73 m2 but eGFRcys < 60 mL/min/1.73 m2 as the detection of hidden renal impairment (DHRI). Cut-off values were determined based on muscle mass for the cases of DHRI suggesting the criteria of cystatin C test in renal function evaluation.

RESULTS

We confirmed significant negative correlation between %difference of eGFRcr from eGFRcys and SMI (r, -0.592 for male, -0.484 for female) or CC (r, -0.646 for male, -0.351 for female). SMI of 7.3 kg/m2 for males and 5.7 kg/m2 for females were suggested to be significant cutoffs for indication of cystatin C test. We also suggested CC would be valuable for cystatin C indication.

CONCLUSION

We suggested the muscle mass-based objective criteria relating to SMI and CC that would indicate the use of cystatin C to evaluate renal function test in sarcopenic cases. Our results highlight the importance of muscle mass-based selection of renal function.

Detection of urinary cystatin-c in IUGR neonates by immunoblot SDS-PAGE

BACKGROUND

it is known that intrauterine growth retardation (IUGR) represents a risk factor for the deterioration of renal function as it can adversely impact on the number of nephrons developed in the kidney during nephrogenesis. An interesting molecule is the Cystatin-C (cyst-C): it is considered to have the potency to detect both glomerular and proximal renal injury. Recently, using a quantitative EIA cyst-C detection kit, we found increased levels of cyst-C in the urine of neonates with IUGR. Since cyst-C molecules can be present in both monomer and/or polymer forms, the purpose of this study is to investigate in which forms this molecule is present in the urine of IUGR neonates by Immunoblot SDS-PAGE in order to verify if the presence or absence of a particular type of cyst-C conformation can give more information about the renal functioning.

METHODS

urine samples were collected from 64 neonates with IUGR, and 86 healthy controls defined as appropriate for gestational age (AGA). Urinary cyst-C was investigated by the Immunoblot SDS-PAGE.

RESULTS

in all urine samples, SDS-PAGE analysis showed a reactivity of the IgG anti cyst-C with a complex of about 70 kDa. The monomer form at 13 KDa appeared in 78% of IUGR neonates and in 12% of AGA neonates.

CONCLUSIONS

this study revealed the presence of monomer cyst-C in the urine of IUGR neonates, and suggests an insufficient and/or non-compensatory reabsorption by tubular cells. Monomeric cyst-C can be considered an early biochemical marker to identify and to select IUGR neonates who need to be monitored for risk of renal injury.

Associations of exposure to melamine, cyanuric acid, phthalates with markers of early kidney impairment, and their interactions in US adults: analyses of NHANES 2003-2004 data

Melamine (MEL), cyanuric acid (CYA), and phthalates have kidney toxicity, respectively. Still, no study has explored whether there is an interaction of co-exposure to MEL, CYA, and phthalates on early kidney impairment, including cystatin C (CYST), beta 2-microglobulin (β2-MG), albumin creatinine ratio (ACR), and estimated glomerular filtration rate (eGFR). Urine samples were collected from 333 adults in the National Health and Nutrition Examination Survey (NHANES) 2003-2004, and urinary MEL, CYA, and ten metabolites of phthalates were quantified. The multiple markers of early kidney impairment were also measured, including serum CYST, β2-MG, urinary ACR, and eGFR. Their associations were explored by multiple linear and multivariate logistic regression models. Meanwhile, the interactions of co-exposure to MEL, CYA, and phthalates on early kidney impairment were analyzed by Wilcoxon rank-sum test combined with the LSD test. In the multiple linear regression model, urinary concentrations of monobenzyl phthalate (MBzP), mono(3-carboxypropyl) phthalate (MCPP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono(2-ethylhexyl) phthalate (MEHP) were positively associated with urinary ACR, serum β2-MG, and CYST, respectively. Urinary concentrations of MBzP and MCPP were negatively associated with eGFR. In the multivariate logistic regression model, increased urinary CYA concentration was the risk factor of CYST abnormality with an odds ratio (OR) (95% confidence interval, 95% CI) of 2.38 (1.01, 5.60) (P = 0.047) and increased urinary MBzP concentration was the risk factor of ACR abnormality with an OR of 2.59 (1.41, 4.75) (P = 0.002). The co-exposure to MEL, CYA, and four phthalate metabolites (MEHP, MBzP, MCPP, and MECPP) presented significantly interactive effects on the markers of early kidney impairment, respectively. There were the independent and interactive effects of exposure to MEL, CYA, and specific phthalate metabolites on early kidney impairment. Due to co-exposure to multiple environmental chemicals in our daily life, more attention should be paid to the health damage raised by the synergistic effects of environmental chemicals.

The Association between Mercury and Lead Exposure and Liver and Kidney Function in Pregnant Surinamese Women Enrolled in the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH) Environmental Epidemiologic Cohort Study

Exposure to mercury (Hg) and lead (Pb) may have an effect on pregnant women. We assessed the effect of exposure to mercury and lead on liver and kidney functions in a subcohort of pregnant women who participated in the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH)—Meki Tamara, study. From 400 women aged 16−46 living in rural, urban, and interior regions of Suriname, we measured blood mercury and blood lead levels. Creatinine, urea, and cystatin C were measured to assess kidney function, and aspartate amino transferase (AST), alanine amino transferase (ALT), and gamma-glutamyl transferase (GGT) were measured to assess liver function. Education, region, and ethnicity showed significant differences for both blood mercury and lead levels, which all had p-values < 0.001. Creatinine and urea were elevated with higher mercury blood levels. Our findings also suggest a relationship between high mercury blood levels and potential harmful effects on liver and kidney function.

Impact of Elevated LDH on Cystatin C-Based Glomerular Filtration Rate Estimates in Patients with Cancer

Background: The determination of renal function is crucial for the clinical management of patients with cancer. The glomerular filtration rate (GFR) serves as a key parameter, estimated by creatinine clearance determination in 24-h collected urine (CrCl) as well as equation-based approaches (eGFR) relying on serum creatinine (eGFR CKD EPIcrea) or serum cystatin C (eGFR cystatin C). Serum creatinine and serum cystatin C levels differentially depend on muscle and tumor mass, respectively. Although muscle and tumor mass may thus represent confounding factors, comparative studies for eGFR estimate approaches in cancer patients are lacking. Methods: The present study retrospectively analyzed GFR estimates based on equations of creatinine (eGFRcr), cystatin C (eGFRcys) and combined creatinine-cystatin C levels (eGFRcr-cys) in a subset of patients. The associations of LDH with cystatin C or LDH with eGFRcr, eGFRcys and GFRcr-cys were explored. Results: The laboratory values of 123 consecutive patients were included. The median age was 59 (24−87) and 47.2% were female. There was a statistically significant difference in the mean of CKD EPIcrea (85.17 ± 21.63 mL/min/1.73 m2), CKD EPIcys (61.16 ± 26.03 mL/min/1.73 m2) and CKD EPIcrea-cys (70.42 ± 23.89 mL/min/1.73 m2) (p < 0.0001). Spearman’s correlation analysis revealed a significant correlation of elevated plasma LDH >1.5 UNV and cystatin C values (r = 0.270, p < 0.01, n = 123). LDH values >1.5 UNV were associated with significantly lower CKD EPIcys (r = 0.184, p < 0.01) or CKD EPIcrea-cys (r = 0.226, p < 0.05) estimates compared to CKD EPIcrea. Conclusions: The inclusion of cystatin C as a biomarker led to a lower eGFR estimates compared to creatinine alone or in a combination of both cystatin C and creatinine. The level of cystatin C correlated with the level of LDH, suggesting that the use of cystatin C-based calculations of GFR in cancer patients with elevated LDH should be used with caution.

Application of New Acute Kidney Injury Biomarkers

Kidney-related biomarkers can provide structural and functional information about different parts of the nephron. These biomarkers can be used to evaluate glomerular, tubular, or interstitial injury, inflammation, or repair, and glomerular or tubular function. Furthermore, biomarkers can improve the acute kidney injury diagnosis in various clinical conditions, including acute interstitial nephritis, acute tubular injury, hepatorenal and cardiorenal syndrome, ischemic and nephrotoxic acute kidney injury, and drug-induced acute kidney injury. Biomarkers might be used as an additional precision medicine tool in managing patients with acute kidney injury; they can help with clinical decision-making and impact patient outcomes. In this chapter, we reviewed the utility of biomarkers used in acute kidney injury.

Mapping the Serum Proteome of COVID-19 Patients; Guidance for Severity Assessment

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), whose outbreak in 2019 led to an ongoing pandemic with devastating consequences for the global economy and human health. According to the World Health Organization, COVID-19 has affected more than 481 million people worldwide, with 6 million confirmed deaths. The joint efforts of the scientific community have undoubtedly increased the pace of production of COVID-19 vaccines, but there is still so much uncharted ground to cover regarding the mechanisms of SARS-CoV-2 infection, replication and host response. These issues can be approached by proteomics with unprecedented capacity paving the way for the development of more efficient strategies for patient care. In this study, we present a deep proteome analysis that has been performed on a cohort of 72 COVID-19 patients aiming to identify serum proteins assessing the dynamics of the disease at different age ranges. A panel of 53 proteins that participate in several functions such as acute-phase response and inflammation, blood coagulation, cell adhesion, complement cascade, endocytosis, immune response, oxidative stress and tissue injury, have been correlated with patient severity, suggesting a molecular basis for their clinical stratification. Eighteen protein candidates were further validated by targeted proteomics in an independent cohort of 84 patients including a group of individuals that had satisfactorily resolved SARS-CoV-2 infection. Remarkably, all protein alterations were normalized 100 days after leaving the hospital, which further supports the reliability of the selected proteins as hallmarks of COVID-19 progression and grading. The optimized protein panel may prove its value for optimal severity assessment as well as in the follow up of COVID-19 patients.

Targeted Cancer Therapies Causing Elevations in Serum Creatinine Through Tubular Secretion Inhibition: A Case Report and Review of the Literature

Rationale:

Targeted cancer therapies have revolutionized the field of oncology by selecting for specific molecular pathways, thus improving overall clinical prognosis. However, many of these targeted treatments have been reported to have adverse kidney effects, including acute kidney injury, interstitial nephritis, and glomerular disease. Furthermore, some of these targeted therapies have also been found to cause an asymptomatic rise in serum creatinine levels through inhibition of active tubular secretion.

Presenting concerns:

A 79-year-old woman was being followed for stage 4 A2 chronic kidney disease secondary to type 2 diabetes and longstanding hypertension. She was diagnosed with invasive mammary carcinoma and was initiated on letrozole, an aromatase inhibitor, and palbociclib, a selective cyclin-dependent kinase inhibitor, was subsequently added. Prior to the initiation of her treatments, her baseline estimated glomerular filtration rate (eGFR) fluctuated between 25 and 28 mL/min/1.73 m² over the previous year. After initiating palbociclib, her serum creatinine progressively increased, despite having well-controlled blood pressure and diabetes. In addition, there was no history of pre-renal events nor any sonographic evidence of obstruction. Within 7 months, her eGFR based on serum creatinine had decreased down to 12 mL/min/1.73 m².

Interventions:

Given that there were no clinical or other biochemical changes suggestive of worsening renal function, a serum cystatin C was measured using an immunoturbidimetric assay, which was 1.71 mg/L and correlated with an eGFR of 33 mL/min/1.73 m² based on the chronic kidney disease epidemiology collaboration (CKD-EPI) cystatin C equation (2012). This value was consistent with her previous baseline. Based on these findings, the significant decrease in eGFR measured by serum creatinine was attributed to the inhibitory effects of palbociclib on tubular creatinine secretion, rather than representing true kidney damage. Thus, a kidney biopsy was not performed in this context.

Outcomes:

Seven months later, a repeat serum cystatin C was repeated to assess for any worsening of the patient’s kidney function and revealed an eGFR of 35 mL/min/1.73 m² based on the CKD-EPI cystatin C equation (2012), thus revealing stable kidney function and reinforcing the inhibitory effects of palbociclib on tubular creatinine secretion through its direct effects on kidney transporters.

Teaching points:

This case report and literature review acknowledges the importance of using alternative methods of assessing kidney function when patients are undergoing targeted cancer therapies known to affect tubular creatinine secretion, which include cyclin-dependent kinase 4/6 inhibitors, poly(adenosine diphosphate-ribose) polymerase inhibitors, tyrosine kinase inhibitors, and mesenchymal-epithelial transition inhibitors. The use of non–creatinine-based markers of glomerular filtration rate (GFR), such as cystatin C and nuclear renal scans, will allow for more accurate estimation of kidney function in the appropriate setting, thus avoiding invasive diagnostic tests and unnecessary adjustments of treatment plans. However, certain targeted cancer therapies have also been proven to cause true kidney injury; therefore, physicians must still maintain a high degree of suspicion and consider invasive investigations and/or cessation or reduction of treatments when alternative measurements of kidney function do not suggest an underestimation of GFR via serum creatinine.

The neural stem cell secretome across neurodevelopment

Neural stem cell (NSC) based therapies are at the forefront of regenerative medicine strategies to combat illness and injury of the central nervous system (CNS). In addition to their ability to produce new cells, NSCs secrete a variety of products, known collectively as the NSC secretome, that have been shown to ameliorate CNS disease pathology and promote recovery. As pre-clinical and clinical research to harness the NSC secretome for therapeutic purposes advances, a more thorough understanding of the endogenous NSC secretome can provide useful insight into the functional capabilities of NSCs. In this review, we focus on research investigating the autocrine and paracrine functions of the endogenous NSC secretome across life. Throughout development and adulthood, we find evidence that the NSC secretome is a critical component of how endogenous NSCs regulate themselves and their niche. We also find gaps in current literature, most notably in the clinically-relevant domain of endogenous NSC paracrine function in the injured CNS. Future investigations to further define the endogenous NSC secretome and its role in CNS tissue regulation are necessary to bolster our understanding of NSC-niche interactions and to aid in the generation of safe and effective NSC-based therapies.

A risk prediction model for acute kidney injury in patients with pulmonary tuberculosis during anti-tuberculosis treatment

Background

Acute kidney injury (AKI) is not a rare complication during anti-tuberculosis treatment in some patients with pulmonary tuberculosis (PTB). We aimed to develop a risk prediction model for early recognition of patients with PTB at high risk for AKI during anti-TB treatment.

Methods

This retrospective cohort study assessed the clinical baseline, and laboratory test data of 315 inpatients with active PTB who were screened for predictive factors from January 2019 to June 2020. The elements were analyzed by logistic regression analysis. A nomogram was established by the results of the logistic regression analysis. The prediction model discrimination and calibration were evaluated by the concordance index (C-index), ROC curve, and Hosmer-Lemeshow analysis.

Results

A total of 315 patients with PTB were enrolled (67 patients with AKI and 248 patients without AKI). Seven factors, including microalbuminuria, hematuria, cystatin-C (CYS-C), albumin (ALB), creatinine-based estimated glomerular filtration rates (eGFRs), body mass index (BMI), and CA-125 were acquired to develop the predictive model. According to the logistic regression, microalbuminuria (OR = 3.038, 95%CI 1.168–7.904), hematuria (OR = 3.656, 95%CI 1.325–10.083), CYS-C (OR = 4.416, 95%CI 2.296–8.491), and CA-125 (OR = 3.93, 95%CI 1.436–10.756) were risk parameter, while ALB (OR = 0.741, 95%CI 0.650–0.844) was protective parameter. The nomogram demonstrated good prediction in estimating AKI (C-index= 0.967, AUC = 0.967, 95%CI (0.941–0.984), sensitivity = 91.04%, specificity = 93.95%, Hosmer-Lemeshow analysis SD = 0.00054, and quantile of absolute error = 0.049).

Conclusions

Microalbuminuria, hematuria, ALB reduction, elevated CYS-C, and CA-125 are predictive factors for the development of AKI in patients with PTB during anti-TB treatments. The predictive nomogram based on five predictive factors is achieved good risk prediction for AKI during anti-TB treatments.

Changes in Mortality According to Creatinine/Cystatin C Ratio in Chronic Kidney Disease and Non-chronic Kidney Disease Patients

Background

Serum creatinine and cystatin C are not only good indicators of renal function but have also been confirmed to be related to disease prognosis and mortality in various diseases via creatinine/cystatin C ratio (CCR). However, although they are biomarkers of renal function, there is no study regarding renal impairment as a confounding variable in the relationship between CCR and all-cause mortality.

Methods

Patients who had simultaneous measurements of serum creatinine and cystatin C between 2003 and 2020 were enrolled. The patients with chronic kidney disease (CKD) were defined as having an estimated glomerular filtration rate (eGFR) CKD-EPI Cr-Cystatin C < 60 ml/min/1.73 m². CCR was calculated by dividing the serum creatinine level by the cystatin C level measured on the same day. The main outcome assessed was all-cause mortality according to CCR in CKD or non-CKD groups.

Results

Among the 8,680 patients in whom creatinine and cystatin C levels were measured simultaneously, 4,301 were included in the CKD group, and 4,379 were included in the non-CKD group, respectively. CCR was 1.4 ± 0.6 in total participants. The non-CKD group showed higher mean CCR, (1.5 ± 0.7 vs. 1.3 ± 0.5) as well as a wider distribution of CCR (p < 0.001) when compared to the CKD group. In non-CKD group, 1^st, 4^th and 5^th quintiles of CCR significantly increased the all-cause mortality risk compared to 2^nd quintile of CCR, suggesting U-shaped mortality risk according to CCR in non-CKD. On the other hand, in CKD group, the risk of all-cause mortality linearly increased and 5^th quintile of CCR showed 1.82 times risk of mortality compared to 2^nd quintile of CCR. In the subgroup analysis of mortality by age and sex, the mortality difference according to CCR were diminished in old age and female sex subgroups.

Conclusion

We discovered a U-shaped relationship between mortality and CCR levels in normal renal function, and an increased risk of mortality in CKD with elevated CCR.

Estimating Renal Function Following Lung Transplantation

Background: Patients undergoing lung transplantation (LTx) experience a rapid decline in glomerular filtration rate (GFR) in the acute postoperative period. However, no prospective longitudinal studies directly comparing the performance of equations for estimating GFR in this patient population currently exist. Methods: In total, 32 patients undergoing LTx met the study criteria. At pre-LTx and 1-, 3-, and 12-weeks post-LTx, GFR was determined by ⁵¹Cr-EDTA and by equations for estimating GFR based on plasma (P)-Creatinine, P-Cystatin C, or a combination of both. Results: Measured GFR declined from 98.0 mL/min/1.73 m² at pre-LTx to 54.1 mL/min/1.73 m² at 12-weeks post-LTx. Equations based on P-Creatinine underestimated GFR decline after LTx, whereas equations based on P-Cystatin C overestimated this decline. Overall, the 2021 CKD-EPI combination equation had the lowest bias and highest precision at both pre-LTx and post-LTx. Conclusions: Caution must be applied when interpreting renal function based on equations for estimating GFR in the acute postoperative period following LTx. Simplified methods for measuring GFR may allow for more widespread use of measured GFR in this vulnerable patient population.

Quinoline-Based Photolabile Protection Strategy Facilitates Efficient Protein Assembly

Native chemical ligation (NCL) provides a powerful solution to assemble proteins with precise chemical features, which enables a detailed investigation of the protein structure-function relationship. As an extension to NCL, the discovery of desulfurization and expressed protein ligation (EPL) techniques has greatly expanded the efficient access to large or challenging protein sequences via chemical ligations. Despite its superior reliability, the NCL-desulfurization protocol requires orthogonal protection strategies to allow selective desulfurization in the presence of native Cys, which is crucial to its synthetic application. In contrast to traditional thiol protecting groups, photolabile protecting groups (PPGs), which are removed upon irradiation, simplify protein assembly and therefore provide minimal perturbation to the peptide scaffold. However, current PPG strategies are mainly limited to nitro-benzyl derivatives, which are incompatible with NCL-desulfurization. Herein, we present for the first time that quinoline-based PPG for cysteine can facilitate various ligation strategies, including iterative NCL and EPL-desulfurization methods. 7-(Piperazin-1-yl)-2-(methyl)quinolinyl (PPZQ) caging of multiple cysteine residues within the protein sequence can be readily introduced via late-stage modification, while the traceless removal of PPZQ is highly efficient via photolysis in an aqueous buffer. In addition, the PPZQ group is compatible with radical desulfurization. The efficiency of this strategy has been highlighted by the synthesis of γ-synuclein and phosphorylated cystatin-S via one-pot iterative ligation and EPL-desulfurization methods. Besides, successful sextuple protection and deprotection of the expressed Interleukin-34 fragment demonstrate the great potential of this strategy in protein caging/uncaging investigations.

Dimethylarginines in Children after Anti-Neoplastic Treatment

Background and Objectives: According to a recent Cochrane systematic review, renal impairment can develop in 0-84% of childhood cancer survivors in the future. The renal function impairment in this patient group can be related to nephrectomy, nephrotoxic agents therapy, abdominal radiotherapy, and combinations of these treatment methods. In this study, in a population of patients after anti-neoplastic therapy, with particular emphasis on patients after Wilms' tumour treatment, we compared new substances which play role in the chronic kidney disease (CKD) pathogenesis (asymmetric dimethylarginine-ADMA, symmetric dimethylarginine-SDMA) with standard renal function markers (e.g., creatinine and cystatin C in serum, creatinine in urine, etc.) to assess the usefulness of the former. Materials and Methods: Eighty-four children, without CKD, bilateral kidney tumours, congenital kidney defects, or urinary tract infections, with a minimum time of 1 year after ending anti-neoplastic treatment, aged between 17 and 215 months, were divided into three groups: group 1-patients after nephroblastoma treatment (n = 21), group 2-after other solid tumours treatment (n = 44), and group 3-after lymphoproliferative neoplasms treatment (n = 19). The patients' medical histories were taken and physical examinations were performed. Concentrations of blood urea nitrogen (BUN), creatinine, cystatin C, C-reactive protein (CRP), ADMA, and SDMA in blood and albumin in urine were measured, and a general urine analysis was performed. The SDMA/ADMA ratio, albumin-creatine ratio, and estimated glomerular filtration rate (eGFR) were calculated. eGFR was estimated by three equations recommended to the paediatric population by the KDIGO from 2012: the Schwartz equation (eGFR1), equation with creatinine and urea nitrogen (eGFR2), and equation with cystatin C (eGFR3). Results: Both the eGFR1 and eGFR2 values were significantly lower in group 1 than in group 3 (eGFR1: 93.3 (83.1-102.3) vs. 116.5 (96.8-126.9) mL/min/1.73 m2, p = 0.02; eGFR2: 82.7 (±14.4) vs. 94.4 (±11.9) mL/min/1.73 m2, p = 0.02). Additionally, there were weak positive correlations between SDMA and creatinine (p < 0.05, r = 0.24), and cystatin C (p < 0.05, r = 0.32) and weak negative correlations between SDMA and eGFR1 (p < 0.05, r = -0.25), eGFR2 (p < 0.05, r = -0.24), and eGFR3 (p < 0.05, r = -0.32). Conclusions: The usefulness of ADMA and SDMA in the diagnosis of renal functional impairment should be assessed in further studies. eGFR, calculated according to equations recommended for children, should be used in routine paediatric practice.

A high triglyceride glucose index is associated with early renal impairment in the hypertensive patients

OBJECTIVE

Serum β2-microglobulin (β2-MG) and serum cystatin C (CysC) are sensitive and reliable indicators of early renal impairment. Triglyceride glucose index (TyG) is an emerging vital indicator of insulin resistance and is associated with increased risk of hypertension. We aimed to analyze the relationship between TyG and early renal impairment in hypertensive patients.

METHODS

A retrospective analysis was performed on 881 hypertensive patients treated in Qinghai Provincial People, s Hospital from March 2018 to March 2021, their clinical data and corresponding laboratory index values were recorded, and the TyG index was calculated. According to the TyG index, the patients were divided into a low TyG (L-TyG) group (TyG ≤ 8.50, n=306), medium TyG (M-TyG) group (8.51≤TyG ≤ 8.94, n=281), and high TyG (H-TyG) group (TyG>8.95, n=294) in sequence by using tertiles. Then, according to serum β2-MG and CysC levels, they were divided into a normal renal function group (β2-MG ≤ 2.4 mg/L, n=700 and CysC ≤ 1.25mg/L, n=721) and a renal function injury group (β2-MG>2.4 mg/L, n=181, and CysC>1.25 mg/L, n=160). Multivariate linear regression analysis was used to analyze the influencing factors of serum β2-microglobulin and cystatin C. Multivariate Logistic regression was used to analyze the relationship between the TyG index and early renal impairment in hypertensive patients. The receiver operating characteristic curve (ROC) was used to determine the value of the TyG index in predicting early renal impairment in patients with hypertension.

RESULT

As the TyG index level increased, serum β2-MG and CysC levels also gradually increased. Multivariate linear regression analysis showed that TyG index was the influencing factor of serum β2-MG (B=0.060, P=0.007) and serum CysC (B=0.096, P<0.001). For every 1 standard deviation increase in the TyG index, the serum β2-MG and CysC increased by 0.06mg/L and 0.096mg/L, respectively. When compared to the normal group, the TyG level (8.91 ± 0.65 vs 8.64 ± 0.60, P<0.001) was higher in the renal impairment group with β2-MG>2.4 mg/L. The results of multivariate logistic regression analysis revealed that for every 1 standard deviation increase in the TyG index, the risk of early renal impairment in hypertensive patients increased 1.53 times (OR=1.53, 95%CI 1.006-2.303).The ROC curves showed that the TyG index was not superior to TG in predicting early renal impairment in hypertensive patients. the AUC values were 0.623 and 0.617, respectively. Then, when CysC>1.25 mg/L was used as the renal damage group, the level of TyG was still higher than that in the normal group (8.94 ± 0.67 and 8.64 ± 0.60, P<0.001). Multivariate Logistic regression analysis showed that for every 1 standard deviation increase in the TyG index, the risk of early renal impairment in hypertensive patients increased 2.82 times (OR=2.82, 95%CI 1.863-4.262). The ROC curves showed that the TyG index was not superior to TG in predicting early renal impairment in hypertensive patients. the AUC values were 0.629 and 0.626, respectively.

CONCLUSION

TyG index is an influential factor in serum β2-MG and CysC levels. The elevated TyG index levels are closely associated with the occurrence and development of early renal impairment in hypertensive patients, but it should be used cautiously in the prediction of early renal impairment.

Association between serum cystatin C level and hemodynamically significant aortic stenosis: a prospective cohort study

BACKGROUND

Cystatin C (CysC) is a cysteine protease inhibitor involved in proteins catabolism and plays an essential role in human vascular pathophysiology. CysC may also increase the risk of aortic stenosis (AS), but limited studies have reported on this association. This study aimed to investigate if elevated serum CysC levels are associated with hemodynamically significant AS.

METHODS

Serum CysC levels were estimated in 4,791 participants, samples were collected in 1990-1992. The study population was divided into quintile groups. Follow-up continued in 2011-2013 when participants returned for echocardiography examination. Incidence of aortic valve disease (AVD) was ascertained by Doppler echocardiography through the end of 2013. AVD defined in hemodynamic progression was assessed and classified as aortic sclerosis, mild stenosis, and moderate-to-severe stenosis.

RESULTS

Overall, a total of 4,791 participants (mean age: 54.8 ± 5.0 years, females: 57.6%, blacks: 8.2%) were included in this study. During a follow-up of 21 years, we identified 736 cases (15.4%) of aortic sclerosis, 194 cases (4.0%) of mild stenosis, and 42 cases (0.7%) of moderate-to-severe stenosis. Compared with serum CysC levels within individual quintile groups, the odds ratio (OR) was per standard deviation associated with an increased incidence of AVD (OR = 1.15, 95% CI: 1.05-1.26,P = 0.002).

CONCLUSIONS

In this large population-based study, an increased serum CysC levels is independently associated with the incidence of hemodynamically significant AS. However, this association appears not to extend to patients with extremely high serum CysC levels and necessitate further investigation.

Pathway Association Studies Reveal Gene Loci and Pathway Networks that Associated With Plasma Cystatin C Levels

As a marker for glomerular filtration, plasma cystatin C level is used to evaluate kidney function. To decipher genetic factors that control the plasma cystatin C level, we performed genome-wide association and pathway association studies using United Kingdom Biobank data. One hundred fifteen loci yielded p values less than 1 × 10⁻¹⁰⁰, three genes (clusters) showed the most significant associations, including the CST8-CST9 cluster on chromosome 20, the SH2B3-ATXN2 gene region on chromosome 12, and the SHROOM3-CCDC158 gene region on chromosome 4. In pathway association studies, forty significant pathways had FDR (false discovery rate) and or FWER (family-wise error rate) ≤ 0.001: spermatogenesis, leukocyte trans-endothelial migration, cell adhesion, glycoprotein, membrane lipid, steroid metabolic process, and insulin signaling pathways were among the most significant pathways that associated with the plasma cystatin C levels. We also performed Genome-wide association studies for eGFR, top associated genes were largely overlapped with those for cystatin C.

The predictive value of serum level of cystatin C for COVID-19 severity

To investigate the potential prognostic value of Serum cystatin C (sCys C) in patients with COVID-19 and determine the association of sCys C with severe COVID-19 illness. We performed a retrospective review of medical records of 162 (61.7 ± 13.5 years) patients with COVID-19. We assessed the predictive accuracy of sCys C for COVID-19 severity by the receiver operating characteristic (ROC) curve analysis. The participants were divided into two groups based on the sCys C cut-off value. We evaluated the association between high sCys C level and the development of severe COVID-19 disease, using a COX proportional hazards regression model. The area under the ROC curve was 0.708 (95% CI 0.594-0.822), the cut-off value was 1.245 (mg/L), and the sensitivity and specificity was 79.1% and 60.7%, respectively. A multivariable Cox analysis showed that a higher level of sCys C (adjusted HR 2.78 95% CI 1.25-6.18, p = 0.012) was significantly associated with an increased risk of developing a severe COVID-19 illness. Patients with a higher sCys C level have an increased risk of severe COVID-19 disease. Our findings suggest that early assessing sCys C could help to identify potential severe COVID-19 patients.

The Role of GPR15 Function in Blood and Vasculature

Since the first prominent description of the orphan G protein-coupled receptor 15 (GPR15) on lymphocytes as a co-receptor for the human immunodeficiency virus (HIV) type 1 and 2 and the first report about the GPR15-triggered cytoprotective effect on vascular endothelial cells by recombinant human thrombomodulin, several decades passed before the GPR15 has been recently deorphanized. Because of new findings on GPR15, this review will summarize the consequences of GPR15 signaling considering the variety of GPR15-expressing cell types and of GPR15 ligands, with a focus on blood and vasculature.

Natural sweetener Stevia rebaudiana: Functionalities, health benefits and potential risks

Stevia rebaudiana is a South American plant, the cultivation of which is increasing worldwide due to its high content of sweet compounds. Stevia sweetness is mainly due to steviol glycosides, that are ~250-300 times sweeter than sucrose. Many studies have suggested the benefits of Stevia extract over sugar and artificial sweeteners, but it is still not a very popular sugar substitute. This review summarizes current data on the biological activities of S. rebaudiana extract and its individual glycosides, including anti-hypertensive, anti-obesity, anti-diabetic, antioxidant, anti-cancer, anti-inflammatory, and antimicrobial effects and improvement of kidney function. Possible side effects and toxicity of Stevia extract are also discussed.

The role of cystatin C in multiple myeloma

INTRODUCTION

Renal insufficiency is one of the common complications in multiple myeloma (MM) and an independent factor indicating a poor prognosis. Cystatin C (Cys C) is considered to be expected to replace creatinine to calculate glomerular filtration rate due to its own characteristics. Gene expression analysis suggested that cystatin C is up-regulated nearly 50-fold in patients with multiple myeloma.

METHODS

To further clarify the role of cystatin C in multiple myeloma, we retrospectively evaluated pretreatment cystatin C levels in 195 newly diagnosed patients through statistical analysis.

RESULTS

The elevation of serum cystatin C was positively related to the elevation of serum creatinine (P < .001), LDH (P = .006), β2-microglobulin (P < .001), bone marrow plasma cell proportion (P = .005) and the reduction of hemoglobin levels (P < .001). Patients with serum cystatin C levels >1.6 mg/L had a significantly shorter progression-free survival (PFS) or overall survival (OS) than patients with serum cystatin C levels <1.6 mg/L (median PFS: median unreached vs 16.7 months, P < .001; median OS: 68 months vs 42 months, P = .014). Although serum cystatin C is not an independent prognostic factor of OS and PFS in patients with multiple myeloma, serum cystatin C can be considered as a sensitive indicator to differentiate well OS and PFS in the group of ISS II patients.

CONCLUSION

Serum cystatin C is associated with tumor burden of multiple myeloma and cystatin C can further differentiate the prognosis of ISS II patients. More prospective studies are required to explore the role of serum cystatin C in multiple myeloma.

Dexmedetomidine reduces acute kidney injury after endovascular aortic repair of Stanford type B aortic dissection: A randomized, double-blind, placebo-controlled pilot study

STUDY OBJECTIVE

To determine the effect of dexmedetomidine on acute kidney injury (AKI) following endovascular aortic repair (EVAR) for Stanford type B aortic dissection (TBAD).

DESIGN

Randomized, double-blind, placebo-controlled, pilot study.

SETTING

University Hospital.

PATIENTS

102 TBAD patients undergoing EVAR procedures were enrolled. Patients with dissection involving aortic arch or renal artery were excluded.

INTERVENTIONS

Patients were randomly assigned, in a 1:1 ratio, to a dexmedetomidine group (intravenous dexmedetomidine 0.4 μg/kg/h immediately after anesthesia induction and 0.1 μg/kg/h after extubation, which was maintained until 24 h) or a normal saline control group.

MEASUREMENTS

The primary outcome was the incidence of AKI within the first two days after surgery, based on the Acute Kidney Injury Network (AKIN) criteria. The secondary outcomes included serum cystatin C and estimated glomerular filtration rate on postoperative days 1, 2, and 7, and in-hospital need for renal replacement therapy (RRT). Long-term outcomes included RRT and all-cause mortality.

MAIN RESULTS

Ninety-eight patients completed the study (dexmedetomidine, n = 48; control, n = 50). AKIN stage 1 AKI occurred in 3/48 (6.3%) patients receiving dexmedetomidine, compared with 11/50 (22%) patients receiving normal saline (odds ratio = 0.24, 95% CI: 0.07 to 0.89, P = 0.041). This difference remained significant after adjusting for baseline covariates (adjusted odds ratio = 0.21, 95% CI: 0.05 to 0.84; P = 0.028). Dexmedetomidine led to a lower serum cystatin C on postoperative day 1 (median [IQR] mg/L: 1.31 [1.02-1.72] vs. 1.58 [1.28-1.96]). There were no between-group differences in other secondary or long-term outcomes. During the follow-up (median = 28.4 months), 1 patient in the dexmedetomidine group and 3 patients in the control group required RRT.

CONCLUSIONS

Dexmedetomidine reduced the incidence of AKI in TBAD patients after EVAR procedures. The long-term benefits of dexmedetomidine in this patient population warrant further investigation.

TRIAL REGISTRATION

ChiCTR-IPR-15006372.

Design and methodology of the chronic kidney disease as a dysmetabolic determinant of disability among older people (CKD-3D) study: a multicenter cohort observational study

Background

Chronic kidney disease (CKD) is a common condition in older people and represents a global health issue since it increases the risk of associated comorbidities and all-cause mortality. Furthermore, older people with reduced renal function might be at higher risk for developing functional limitation and disability. Moreover, the current creatinine-based measures of renal function are influenced by several factors in older population. The aims of the CKD-3D project are to perform an observational study to expand the knowledge about CKD-disability relationship and to investigate the use of novel biomarkers of kidney function.

Methods

An observational, multicenter, prospective cohort study will be conducted in 75 + old patients consecutively admitted to acute care wards of geriatric medicine at participating hospitals. The study planned to enroll 440 patients undergoing clinical and laboratory evaluations at baseline and after 12 months. Face-to-face follow-up at 6 months and telephone follow-up at 3 and 9 months will be carried out. Comprehensive Geriatric Assessment (CGA) and the measurement of Cystatin C, Beta-Trace Protein and Beta2-Microglobulin levels will be included.

Discussion

This study will provide useful information to prevent CKD-related disability by collecting real-life data over 1-year period. The combined approach of CGA and the investigation of innovative existing biomarkers will make it possible to develop new recommendations and guidelines for a patient-centered approach. It is believed that such a study may lead to an improvement of knowledge on CKD in elderly patients and may also have implications in daily clinical practice and in decision-making process.

Greater adherence to the dietary approaches to stop hypertension dietary pattern is associated with preserved muscle strength in patients with autosomal dominant polycystic kidney disease: a single-center cross-sectional study

The present study aimed to determine whether certain diets lower the risk of low muscle strength in patients with autosomal dominant polycystic kidney disease (ADPKD). In this cross-sectional study, outpatient ADPKD patients were enrolled from a tertiary care hospital. Muscle strength was assessed on the basis of handgrip strength (HGS), and dietary pattern indices were calculated using dietary intake data. Among the 68 participants included in this study, 19 (27.9%) had low HGS. Cystatin C concentrations were significantly higher in all participants, and in women in the low compared to the normal HGS group in the unadjusted analyses (P = 0.004). Among analyzed dietary pattern indices, the Dietary Approaches to Stop Hypertension (DASH) score was lower, for all participants and men, in the low compared to the normal HGS group (P < 0.05). Especially, the component score for whole grains of the DASH score was significantly lower in men in the low compared to the normal HGS group in unadjusted analyses. The DASH score was positively correlated with HGS in men (r = 0.387, P = 0.046). In addition, logistic regression analysis showed that the DASH score was negatively associated with low HGS, for all participants (odds ratio = 0.851, P = 0.049) and men (odds ratio = 0.716, P = 0.043), after adjusting for age, sex, and body weight. These findings suggest that the DASH dietary pattern may promote the preservation of muscle strength in ADPKD patients. The DASH diet can be considered as a nutritional strategy to maintain muscle strength and prevent sarcopenia in ADPKD patients.