Cystatin C: immunoregulation role in macrophages infected with Porphyromonas gingivalis.

Background: Periodontitis is a chronic infectious disease, characterized by an exacerbated inflammatory response and a progressive loss of the supporting tissues of the teeth. Porphyromonas gingivalis is a key etiologic agent in periodontitis. Cystatin C is an antimicrobial salivary peptide that inhibits the growth of P. gingivalis. This study aimed to evaluate the antimicrobial activity of this peptide and its effect on cytokine production, nitric oxide (NO) release, reactive oxygen species (ROS) production, and programmed cell death in human macrophages infected with P. gingivalis. Methods: Monocyte-derived macrophages generated from peripheral blood were infected with P. gingivalis (MOI 1:10) and stimulated with cystatin C (2.75 µg/ml) for 24 h. The intracellular localization of P. gingivalis and cystatin C was determined by immunofluorescence and transmission electron microscopy (TEM). The intracellular antimicrobial activity of cystatin C in macrophages was assessed by counting Colony Forming Units (CFU). ELISA assay was performed to assess inflammatory (TNFα, IL-1ß) and anti-inflammatory (IL-10) cytokines. The production of nitrites and ROS was analyzed by Griess reaction and incubation with 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA), respectively. Programmed cell death was assessed with the TUNEL assay, Annexin-V, and caspase activity was also determined. Results: Our results showed that cystatin C inhibits the extracellular growth of P. gingivalis. In addition, this peptide is internalized in the infected macrophage, decreases the intracellular bacterial load, and reduces the production of inflammatory cytokines and NO. Interestingly, peptide treatment increased ROS production and substantially decreased bacterial-induced macrophage apoptosis. Conclusions: Cystatin C has antimicrobial and immuno-regulatory activity in macrophages infected with P. gingivalis. These findings highlight the importance of understanding the properties of cystatin C for its possible therapeutic use against oral infections such as periodontitis.

Estimating eGFR using serum creatinine or cystatin C in healthy Vietnamese population.

Very few studies worldwide have assessed the estimated glomerular filtration rate (eGFR) using serum cystatin C (ScysC) in comparison to the gold standard measured glomerular filtration rate (mGFR) with a gamma camera technique using 99m-Technetium-Diethylene Triaminepentoacetic Acid (99mTc-DTPA). To determine the eGFR formula with the most accurate estimate of glomerular filtration rate when compared with mGFR in a healthy population in Vietnam. We conducted a cross-sectional descriptive study of more than 100 adults without hypertension. The study subjects were examined for general characteristics and blood biochemistry tests to assess eGFR, and the glomerular filtration rate was measured using 99mTc-DTPA with the Gates technique to record mGFR. The estimated values of the eGFR formula were evaluated and compared with the actual mGFR using 99mTechnetium-DTPA. Serum creatinine (Scr) concentration showed a significant difference between males and females: 0.9 ±â€…0.1 versus 0.8 ±â€…0.1 (P < .001), while ScysC concentration did not show this difference. The mGFR in the age groups < 40, 40 to 59, and ≥ 60: 105.0 ±â€…9.9, 94.8 ±â€…8.6, and 93.4 ±â€…10.6, respectively (P < .001). The eGFR-CKD-EPI-cystatin C 2012 formula showed the highest positive correlation with mGFR (ΔGFR = -1.6, R = 0.68, P < .001). eGFR calculated using cystatin C does not require sex adjustment, whereas, for creatinine, sex adjustment is necessary. The eGFR-CKD-Epi-CysC formula showed the lowest difference and a strong correlation with mGFR.

Measured and Estimated Glomerular Filtration Rate to Evaluate Rapid Progression and Changes over Time in Autosomal Polycystic Kidney Disease: Potential Impact on Therapeutic Decision-Making.

Autosomal polycystic kidney disease (ADPKD) is the most common genetic form of kidney failure, reflecting unmet needs in management. Prescription of the only approved treatment (tolvaptan) is limited to persons with rapidly progressing ADPKD. Rapid progression may be diagnosed by assessing glomerular filtration rate (GFR) decline, usually estimated (eGFR) from equations based on serum creatinine (eGFRcr) or cystatin-C (eGFRcys). We have assessed the concordance between eGFR decline and identification of rapid progression (rapid eGFR loss), and measured GFR (mGFR) declines (rapid mGFR loss) using iohexol clearance in 140 adults with ADPKD with ≥3 mGFR and eGFRcr assessments, of which 97 also had eGFRcys assessments. The agreement between mGFR and eGFR decline was poor: mean concordance correlation coefficients (CCCs) between the method declines were low (0.661, range 0.628 to 0.713), and Bland and Altman limits of agreement between eGFR and mGFR declines were wide. CCC was lower for eGFRcys. From a practical point of view, creatinine-based formulas failed to detect rapid mGFR loss (-3 mL/min/y or faster) in around 37% of the cases. Moreover, formulas falsely indicated around 40% of the cases with moderate or stable decline as rapid progressors. The reliability of formulas in detecting real mGFR decline was lower in the non-rapid-progressors group with respect to that in rapid-progressor patients. The performance of eGFRcys and eGFRcr-cys equations was even worse. In conclusion, eGFR decline may misrepresent mGFR decline in ADPKD in a significant percentage of patients, potentially misclassifying them as progressors or non-progressors and impacting decisions of initiation of tolvaptan therapy.

Aortic Stenosis and Renal Function: A Bidirectional Mendelian Randomization Analysis.

BACKGROUND: Large observational studies have demonstrated a clear inverse association between renal function and risk of aortic stenosis (AS). Whether this represents a causal, reverse causal or correlative relationship remains unclear. We investigated this using a bidirectional 2-sample Mendelian randomization approach. METHODS AND RESULTS: We collected summary statistics for the primary analysis of chronic kidney disease (CKD) and AS from genome-wide association study meta-analyses including 480 698 and 653 867 participants, respectively. We collected further genome-wide association study summary statistics from up to 1 004 040 participants for sensitivity analyses involving estimated glomerular filtration rate (eGFR) derived from creatinine, eGFR derived from cystatin C, and serum urea nitrogen. Inverse-variance weighted was the primary analysis method, with weighted-median, weighted-mode, Mendelian randomization-Egger, and Mendelian randomization-Pleiotropy Residual Sum and Outlier as sensitivity analyses. We did not find evidence of a causal relationship between genetically predicted CKD liability as the exposure and AS as the outcome (odds ratio [OR], 0.94 per unit increase in log odds of genetic liability to CKD [95% CI, 0.85-1.04], P=0.26) nor robust evidence of AS liability as the exposure and CKD as the outcome (OR, 1.04 per unit increase in log odds of genetic liability to AS [95% CI, 0.97-1.12], P=0.30). The sensitivity analyses were neutral overall, as were the analyses using eGFR derived from creatinine, eGFR derived from cystatin C, and serum urea nitrogen. All positive controls demonstrated strong significant associations. CONCLUSIONS: The present study did not find evidence of a substantial effect of genetically predicted renal impairment on risk of AS. This has important implications for research efforts that attempt to identify prevention and treatment targets for both CKD and AS.

Inflammatory depression is associated with selective glomerular hypofiltration.

BACKGROUND: Systemic low-grade inflammation may be a pathophysiological mechanism in a subtype of depression. In this study we investigate a novel candidate mechanism of inflammatory depression - Selective Glomerular Hypofiltration Syndromes (SGHS) - which are characterized by a reduced estimated glomerular filtration rate (eGFR) based on cystatin C (cysC) relative to eGFR based on creatinine (crea). SGHS have been associated with increased blood levels of pro-inflammatory markers, but have never been investigated in a sample of depressed individuals. METHOD: The prevalence of SGHS was compared between 313 patients with difficult-to-treat depression and 73 controls. Since there is no single established eGFRcysC/eGFRcrea-ratio cut-off to define SGHS, several cut-offs were investigated in relation to a depression diagnosis, inflammation, and symptom severity. Plasma inflammatory markers tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL)-6, IL-8, and IL-10 were available from 276 depressed patients. We examined mediation effects of IL-6 on the relationship between SGHS and depression. RESULTS: Depressed patients were more likely to have SGHS compared to controls defining SGHS as either eGFRcysC/eGFRcrea-ratio < 0.9 (33.2 % vs 20.5 %, p = 0.035) or < 0.8 (15.7 % vs 5.5 %, p = 0.023). Lower eGFRcysC/eGFRcrea-ratio was associated with higher levels of inflammatory markers in depressed patients. IL-6 partly mediated the relationship between SGHS and depression. CONCLUSION: This is the first study to demonstrate a link between SGHS and inflammatory depression. If replicated in independent and longitudinal cohorts, this may prove to be a relevant pathophysiological mechanism in some cases of depression that could be targeted in future intervention and prevention studies.

The clinical utility of cystatin C based eGFR in assessing renal function among HIV/AIDs patients on ART at Mildmay Uganda.

BACKGROUND: In clinical practice, Measurement of estimated glomerular filtration rates (eGFR) is the gold standard assessing renal function the glomerular filtration rate often estimated from plasma creatinine. Several studies have shown Cystatin C based eGFR (Cys C) to be a better parameter for the diagnosis of impaired renal function. Cystatin C based eGFR has been proposed as a potential renal function marker but its use in HIV&AIDS patients has not been well evaluated. METHODS: A cross sectional study was carried out on 914 HIV&AIDS patients on antiretroviral therapy (ART) attending Mildmay Uganda for care and treatment between January to March 2015. Serum Cystatin C based eGFR was measured using the particle enhanced immunoturbidimetric assay. Creatinine was analyzed using enzymatic Creatinine PAP method and creatinine clearance was calculated according to C&G. RESULTS: The sensitivity of Cystatin C based eGFR was 15.1% (95% CI = 8.4, 24) with specificity 99.3% (95% CI = 98- 99.7). The positive and negative predictive values were 70.0% (95% CI 45.7-88.1) and 91.2% (95% CI 98.11-92.94) respectively. The positive likelihood ratio was 18.81 and negative likelihood ratio was 0.85. Cystatin C based eGFR had diagnostic accuracy of 90.7 and area under curve was 0.768. CONCLUSION: Cystatin C based eGFR exhibited a high specificity and a high positive likelihood ratio in diagnosis of kidney disease among HIV&AIDS patients. Cystatin C based eGFR can be used as a confirmatory test.

Association of cardiac biomarkers with long-term cardiovascular events in a community cohort.

MATERIALS AND METHODS: The study assessed major adverse cardiac events (MACE) (myocardial infarction, coronary artery bypass graft, percutaneous intervention, stroke, and death. Cox proportional hazards models assessed apolipoprotein AI (ApoA1), apolipoprotein B (ApoB), ceramide score, cystatin C, galectin-3 (Gal3), LDL-C, Non-HDL-C, total cholesterol (TC), N-terminal B-type natriuretic peptide (NT proBNP), high-sensitivity cardiac troponin (HscTnI) and soluble interleukin 1 receptor-like 1. In adjusted models, Ceramide score was defined by from N-palmitoyl-sphingosine [Cer(16:0)], N-stearoyl-sphingosine [Cer(18:0)], N-nervonoyl-sphingosine [Cer(24:1)] and N-lignoceroyl-sphingosine [Cer(24:0)]. Multi-biomarker models were compared with C-statistics and Integrated Discrimination Index (IDI). RESULTS: A total of 1131 patients were included. Adjusted NT proBNP per 1 SD resulted in a 31% increased risk of MACE/death (HR = 1.31) and a 31% increased risk for stroke/MI (HR = 1.31). Adjusted Ceramide per 1 SD showed a 13% increased risk of MACE/death (HR = 1.13) and a 29% increased risk for stroke/MI (HR = 1.29). These markers added to clinical factors for both MACE/death (p = 0.003) and stroke/MI (p = 0.034). HscTnI was not a predictor of outcomes when added to the models. DISCUSSION: Ceramide score and NT proBNP improve the prediction of MACE and stroke/MI in a community primary prevention cohort.

In a community cohort, where a wide range of biomarkers were evaluated, Ceramide score provided additive value over traditional cardiac risk factors alone for predicting stroke/MI. NT ProBNP provided additive value in prediction of MACE/death. Other biomarkers failed to improve the discrimination of these models.

Plasma metadherin mRNA expression in bladder cancer.

Urinary bladder cancer (BC) is the ninth most common cancer worldwide. At present, the clinical diagnosis of BC depends on self-reported symptoms, tissue biopsy specimens by cystoscopy and from voided urine cytology. However, cystoscopy is an invasive examination and voided urine cytology has low sensitivity, which might provoke misdiagnosis. The search for cancer biomarkers in blood is worthy of intense attention due to patients' comfort and ease of sampling. This work aimed to study expression of mRNA metadherin (MTDH) in plasma, serum BC specific antigen 1 (BLCA-1) and cystatin C as biomarkers of BC and their relation to different disease stages. This study included 59 BC patients, 11 patients with benign bladder lesion and 18 subjects as normal controls. MTDH expression was assessed by real time polymerase chain reaction, BLCA-1, and cystatin C by the enzyme linked immunosorbent assay. The three biomarkers were elevated in BC patients than patients with benign bladder diseases and controls. Patients with BC grade 3 and 4 had higher cystatin C, BLCA-1 and MTDH in comparison to patients with grade 1 and grade 2 (p=0.000). The receiver operating characteristic curve analysis showed that BLCA-1 at a cutoff point of 32.5 ng/ml and area under the curve of 1.00, had 100% accuracy, 100% sensitivity, 100% specificity, 100% positive predictive values and 100% negative predictive value. In conclusion, BLCA-1 was a better biomarker than cystatin C and MTDH. Cystatin C, BLCA-1 and MTDH levels, can differentiate between benign bladder lesion and BC and correlated with tumor grades.especially with OL-HDF compared to HF-HD, with acceptable albumin loss in the dialysate.

Serum Creatinine-Cystatin C Based Screening of Sarcopenia in Community Dwelling Older Adults: A Cross-Sectional Analysis.

OBJECTIVES: To compare the discriminative capabilities for the manifestation of sarcopenia or physical frailty between serum creatinine- and cystatin C-derived indices among community-dwelling older adults. DESIGN: Cross-sectional study. SETTING: Primary Care and Community. PARTICIPANTS: We utilized a subset of data from the Frail Elderly in the Sasayama-Tamba Area (FESTA) study, which was initiated in 2015 to gather comprehensive information on various health-related parameters among community-dwelling older individuals (age ≥65 years). MEASUREMENTS: Five serum creatinine-cystatin C based indices including the Sarcopenia Index, the serum creatinine/cystatin C ratio, the disparity between serum cystatin-C-based and creatinine-based estimated GFR, the total body muscle mass index (TBMM), and the prediction equation for skeletal muscle mass index (pSMI) were employed. Sarcopenia and physical frailty were identified based on the Asian Working Group for Sarcopenia criteria and the revised Japanese version of the Cardiovascular Health Study criteria, respectively. The receiver operating characteristic (ROC) and logistic regression analyses were performed to assess the discriminative abilities of these tools. RESULTS: In the analysis of 954 participants, 52 (5.5%) were identified with sarcopenia and 35 (3.7%) with physical frailty. Regarding sarcopenia discrimination, TBMM and pSMI both exhibited area under the curve (AUC) values exceeding 0.8 for both men and women. Concerning the identification of physical frailty, AUC values ranged from 0.61 to 0.77 for males and 0.50 to 0.69 for females. In the multivariate logistic regression analyses, only TBMM and pSMI consistently displayed associations with sarcopenia, irrespective of sex (P<0.001, respectively). On the other hand, no consistent associations were observed between the indices and physical frailty. CONCLUSIONS: This study provides a robust association of a serum creatinine- and cystatin C-derived indices, especially TBMM and pSMI, with sarcopenia among community-dwelling older adults. Conversely, the application of these indices for the screening of physical frailty has its constraints, necessitating further investigation.

Predictive effect of estimated glomerular filtrate rate by creatinine or cystatin C on mortality in patients with coronary artery disease.

BACKGROUND: Renal dysfunction leads to poor prognosis of patients with coronary artery disease (CAD). Current studies have reported the prognosis or mortality of various diseases using different estimated glomerular filtrate rate (eGFR) formulas, while the performance of these equations is unclear in CAD patients. We aim to evaluate the predict effect of creatinine-based eGFR (eGFRcr), cystatin C-based eGFR (eGFRcys), and both creatinine and cystatin C-based eGFR (eGFRcr-cys) in CAD patients. METHODS: A total of 23,178 patients with CAD were included from CIN-II cohort study. The association of eGFRcr, eGFRcys and eGFRcr-cys with cardiovascular and all-cause mortality was detected by Cox regression analysis. The predictive effect of eGFRcr, eGFRcys and eGFRcr-cys on mortality was assessed. RESULTS: During a median follow up of 4.3 years, totally 2051 patients (8.8%) experience all-cause mortality, of which 1427 patients (6.2%) died of cardiovascular disease. For the detection of cardiovascular mortality among CAD patients, eGFRcr-cys had high discriminatory capacity with area under the curve (AUC) in receiver operator characteristic analysis of 0.730, which was significantly better than eGFRcr (AUC = 0.707, p < 0.001) and eGFRcys (AUC = 0.719, p < 0.001). Similar results were observed in all-cause mortality. Restricted cubic spline showed a U-shaped association between eGFRcr and all outcomes in patients with both reduced and supranormal eGFR levels, while a L-shaped association in eGFRcys and eGFRcr-cys. CONCLUSIONS: Estimated GFR based on both creatinine and cystatin C has highest predictive effect for cardiovascular and all-cause mortality among CAD patients. Meanwhile, supranormal eGFRcr may indicate a higher risk of mortality.

Serum cystatin C and stroke risk: a national cohort and Mendelian randomization study.

Purpose: The debate over the causal and longitudinal association between cystatin C and stroke in older adults persists. Our aim was to assess the link between cystatin C levels, both measured and genetically predicted, and stroke risk. Methods: This study employed a retrospective cohort design using samples of the China Health and Retirement Longitudinal Study (CHARLS), which is a nationally representative cohort recruiting individuals aged 45 years or above. A multivariate logistic model and the two-sample Mendelian randomization framework were used to investigate the longitudinal and genetically predicted effect of serum cystatin C on stroke. Results: The study population had a mean age of 59.6 (SD ±9.5), with 2,996 (46.1%) women. After adjusting for confounding factors, compared to those in the first quartile of cystatin C, those in the last quartile had the greatest risk of stroke incidence [odds ratio (OR), 1.380; 95% confidence interval (CI), 1.046-1.825]. The Mendelian randomization analysis showed that a genetically predicted cystatin C level was positively associated with total stroke (OR by inverse variance-weighted method, 1.114; 95% CI, 1.041-1.192). Conclusions: This national cohort study suggests that higher serum cystatin C is associated with an increased risk of total stroke, which is further supported by Mendelian randomization.

Shenkang injection for the treatment of acute kidney injury: a systematic review and meta-analysis.

OBJECTIVE: Shenkang injection (SKI) has been widely used in China for many years for the treatment of kidney disease. The objective of this systematic review was to assess the efficacy of Shenkang injection for the treatment of acute kidney injury (AKI). METHODS: A search was conducted across seven databases, encompassing data from the inception of each database through October 8th, 2023. Randomized controlled trials comparing SKI-treated AKI patients with control subjects were extracted. The main outcome measure was serum creatinine (SCr) levels. Secondary outcomes included blood urea nitrogen (BUN), serum cystatin C (CysC), 24-h urine protein (24 h-Upro) levels, APACHE II score and adverse reactions. RESULTS: This meta-analysis included eleven studies, and the analysis indicated that, compared with the control group, SKI significantly decreased SCr [WMD = -23.31, 95% CI (-28.06, -18.57); p < 0.001]; BUN [WMD = -2.07, 95% CI (-2.56, -1.57); p < 0.001]; CysC [WMD = -0.55, 95% CI (-0.78, -0.32), p < 0.001]; 24-h urine protein [WMD = -0.43, 95% CI (-0.53, -0.34), p < 0.001]; and the APACHE II score [WMD = -3.07, 95% CI (-3.67, -2.48), p < 0.001]. There was no difference in adverse reactions between the SKI group and the control group [RR = 1.32, 95% CI (0.66, 2.63), p = 0.431]. CONCLUSION: The use of SKI in AKI patients may reduce SCr, BUN, CysC, 24-h Upro levels, and APACHE II scores in AKI patients. The incidence of adverse reactions did not differ from that in the control group. Additional rigorous clinical trials will be necessary in the future to thoroughly evaluate and establish the effectiveness of SKI in the treatment of AKI.

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.

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.

A study of size-selective renal elimination using a novel human model.

The recently discovered selective glomerular hypofiltration syndromes have increased interest in the actual elimination of molecules in the human kidney. In the present study, a novel human model was introduced to directly measure the single-pass renal elimination of molecules of increasing size. Plasma concentrations of urea, creatinine, C-peptide, insulin, pro-BNP, ß2-microglobulin, cystatin C, troponin-T, orosomucoid, albumin, and IgG were analysed in arterial and renal venous blood from 45 patients undergoing Transcatheter Aortic Valve Implantation (TAVI). The renal elimination ratio (RER) was calculated as the arteriovenous concentration difference divided by the arterial concentration. Estimated glomerular filtration rate (eGFR) was calculated by the CKD-EPI equations for both creatinine and cystatin C. Creatinine (0.11 kDa) showed the highest RER (21.0 ± 6.3%). With increasing molecular size, the RER gradually decreased, where the RER of cystatin C (13 kDa) was 14.4 ± 5.3% and troponin-T (36 kDa) was 11.3 ± 4.6%. The renal elimination threshold was found between 36 and 44 kDa as the RER of orosomucoid (44 kDa) was -0.2 ± 4.7%. The RER of creatinine and cystatin C showed a significant and moderate positive linear relationship with eGFR (r = 0.48 and 0.40). In conclusion, a novel human model was employed to demonstrate a decline in renal elimination with increasing molecular size. Moreover, RERs of creatinine and cystatin C were found to correlate with eGFR, suggesting the potential of this model to study selective glomerular hypofiltration syndromes.

Plasma neutrophil gelatinase-associated lipocalin independently predicts dialysis need and mortality in critical COVID-19.

Neutrophil gelatinase-associated lipocalin (NGAL) is a novel kidney injury and inflammation biomarker. We investigated whether NGAL could be used to predict continuous renal replacement therapy (CRRT) and mortality in critical coronavirus disease 2019 (COVID-19). This prospective multicenter cohort study included adult COVID-19 patients in six intensive care units (ICUs) in Sweden between May 11, 2020 and May 10, 2021. Blood was sampled at admission, days two and seven in the ICU. The samples were batch analyzed for NGAL, creatinine, and cystatin c after the end of the study period. Initiation of CRRT and 90-day survival were used as dependent variables in regression models. Of 498 included patients, 494 were analyzed regarding CRRT and 399 were analyzed regarding survival. Seventy patients received CRRT and 154 patients did not survive past 90 days. NGAL, in combination with creatinine and cystatin c, predicted the subsequent initiation of CRRT with an area under the curve (AUC) of 0.95. For mortality, NGAL, in combination with age and sex, had an AUC of 0.83. In conclusion, NGAL is a valuable biomarker for predicting subsequent initiation of CRRT and 90-day mortality in critical COVID-19. NGAL should be considered when developing future clinical scoring systems.

Bias and Accuracy of Glomerular Filtration Rate Estimating Equations in the US: A Systematic Review and Meta-Analysis.

Importance: There is increasing concern that continued use of a glomerular filtration rate (GFR) estimating equation adjusted for a single racial group could exacerbate chronic kidney disease-related disparities and inequalities. Objective: To assess the performance of GFR estimating equations across varied patient populations. Data Sources: PubMed, Embase, Web of Science, ClinicalTrials.gov, and Scopus databases were systematically searched from January 2012 to February 2023. Study Selection: Inclusion criteria were studies that compared measured GFR with estimated GFR in adults using established reference standards and methods. A total of 6663 studies were initially identified for screening and review. Data Extraction and Synthesis: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 2 authors independently extracted data on studies that examined the bias and accuracy of GFR estimating equations. For each outcome, a random-effects model was used to calculate pooled estimates. Data analysis was conducted from March to December 2023. Main Outcomes and Measures: The primary outcomes were bias and accuracy of estimated GFRs in Black vs non-Black patients, as well as in individuals with chronic conditions. Bias was defined as the median difference between the measured GFR and the estimated GFR. Accuracy was assessed with P30 (the proportion of persons in a data set whose estimated GFR values were within 30% of measured GFR values) and measures of heterogeneity. Results: A total of 12 studies with a combined 44 721 patients were included. Significant heterogeneity was found in the bias of various GFR estimation equations. Race-corrected equations and creatinine-based equations tended to overestimate GFR in Black populations and showed mixed results in non-Black populations. For creatinine-based equations, the mean bias in subgroup analysis was 2.1 mL/min/1.73 m2 (95% CI, -0.2 mL/min/1.73 m2 to 4.4 mL/min/1.73 m2) in Black persons and 1.3 mL/min/1.73 m2 (95% CI, 0.0 mL/min/1.73 m2 to 2.5 mL/min/1.73 m2) in non-Black persons. Equations using only cystatin C had small biases. Regarding accuracy, heterogeneity was high in both groups. The overall P30 was 84.5% in Black persons and 87.8% in non-Black persons. Creatinine-based equations were more accurate in non-Black persons than in Black persons. For creatinine-cystatin C equations, the P30 was higher in non-Black persons. There was no significant P30 difference in cystatin C-only equations between the 2 groups. In patients with chronic conditions, P30 values were generally less than 85%, and the biases varied widely. Conclusions and Relevance: This systematic review and meta-analysis of GFR estimating equations suggests that there is bias in race-based GFR estimating equations, which exacerbates kidney disease disparities. Development of a GFR equation independent of race is a crucial starting point, but not the sole solution. Addressing the disproportionate burden of kidney failure on Black individuals in the US requires an enduring, multifaceted approach that should include improving diagnostics, tackling social determinants of health, confronting systemic racism, and using effective disease prevention and management strategies.

The Difference Between Cystatin C- and Creatinine-Based Estimated Glomerular Filtration Rate and Risk of Diabetic Microvascular Complications Among Adults With Diabetes: A Population-Based Cohort Study.

OBJECTIVE: The impact of the difference between cystatin C- and creatinine-based estimated glomerular filtration rate (eGFRdiff) on diabetic microvascular complications (DMCs) remains unknown. We investigated the associations of eGFRdiff with overall DMCs and subtypes, including diabetic retinopathy (DR), diabetic kidney disease (DKD), and diabetic neuropathy (DN). RESEARCH DESIGN AND METHODS: This prospective cohort study included 25,825 participants with diabetes free of DMCs at baseline (2006 to 2010) from the UK Biobank. eGFRdiff was calculated using both absolute difference (eGFRabdiff) and the ratio (eGFRrediff) between cystatin C- and creatinine-based calculations. Incidence of DMCs was ascertained using electronic health records. Cox proportional hazards regression models were used to evaluate the associations of eGFRdiff with overall DMCs and subtypes. RESULTS: During a median follow-up of 13.6 years, DMCs developed in 5,753 participants, including 2,752 cases of DR, 3,203 of DKD, and 1,149 of DN. Each SD decrease of eGFRabdiff was associated with a 28% higher risk of overall DMCs, 14% higher risk of DR, 56% higher risk of DKD, and 29% higher risk of DN. For each 10% decrease in eGFRrediff, the corresponding hazard ratios (95% CIs) were 1.16 (1.14, 1.18) for overall DMCs, 1.08 (1.05, 1.11) for DR, 1.29 (1.26, 1.33) for DKD, and 1.17 (1.12, 1.22) for DN. The magnitude of associations was not materially altered in any of the sensitivity analyses. CONCLUSIONS: Large eGFRdiff was independently associated with risk of DMCs and its subtypes. Our findings suggested monitoring eGFRdiff in the diabetes population has potential benefit for identification of high-risk patients.