Tubular Dickkopf-3 promotes the development of renal atrophy and fibrosis

DKK3 promotes renal fibrosis by increasing MFF-mediated mitochondrial dysfunction in Wnt/β-catenin pathway-dependent manner

BACKGROUND

Chronic kidney disease (CKD) lacks effective treatments and renal fibrosis (RF) is one of CKD's outcomes. Dickkopf 3 (DKK3) has been identified as an agonist in CKD. However, the underlying mechanisms of DKK3 in CKD are not fully understood.

METHODS

H2O2-treated HK-2 cells and ureteric obstruction (UUO) mice were used as RF models. Biomarkers, Masson staining, PAS staining, and TUNEL were used to assess kidney function and apoptosis. Oxidative stress and mitochondria function were also evaluated. CCK-8 and flow cytometry were utilized to assess cell viability and apoptosis. Western blotting, IHC, and qRT-PCR were performed to detect molecular expression levels. Immunofluorescence was applied to determine the subcellular localization. Dual luciferase assay, MeRIP, RIP, and ChIP were used to validate the m6A level and the molecule interaction.

RESULTS

DKK3 was upregulated in UUO mouse kidney tissue and H2O2-treated HK-2 cells. Knockdown of DKK3 inhibited oxidative stress, maintained mitochondrial homeostasis, and alleviated kidney damage and RF in UUO mice. Furthermore, DKK3 silencing suppressed HK-2 cell apoptosis, oxidative stress, and mitochondria fission. Mechanistically, DKK3 upregulation was related to the high m6A level regulated by METTL3. DKK3 activated TCF4/β-catenin and enhanced MFF transcriptional expression by binding to its promoter. Overexpression of MFF reversed in the inhibitory effect of DKK3 knockdown on cell damage.

CONCLUSION

Upregulation of DKK3 caused by m6A modification activated the Wnt/β-catenin pathway to increase MFF transcriptional expression, leading to mitochondrial dysfunction and oxidative stress, thereby promoting RF progression.

Association of urinary excretion rates of uric acid with biomarkers of kidney injury in patients with advanced chronic kidney disease

BACKGROUND

The potential influence of hyperuricemia on the genesis and progression of chronic kidney disease (CKD) remains controversial. In general, the correlation between blood levels of uric acid (UA) and the rate of progression of CKD is considered to be modest, if any, and the results of relevant trials oriented to disclose the effect of urate-lowering therapies on this outcome have been disappointing. Urinary excretion rates of UA could reflect more accurately the potential consequences of urate-related kidney injury.

METHOD

Using a cross-sectional design, we investigated the correlation between different estimators of the rates of urinary excretion of UA (total 24-hour excretion, mean urinary concentration, renal clearance and fractional excretion)(main study variables), on one side, and urinary levels of selected biomarkers of kidney injury and CKD progression (DKK3, KIM1, NGAL, interleukin 1b and MCP)(main outcome variables), in 120 patients with advanced CKD (mean glomerular filtration rate 21.5 mL/minute). We took into consideration essential demographic, clinical and analytic variables with a potential confounding effect on the explored correlations (control variables). Spearman's rho correlation and nonlinear generalized additive regression models (GAM) with p-splines smoothers were used for statistical analysis.

MAIN RESULTS

Multivariate analysis disclosed independent correlations between urinary UA concentrations, clearances and fractional excretion rates (but not plasma UA or total 24-hour excretion rates of UA), on one side, and the scrutinized markers. These correlations were more consistent for DKK3 and NGAL than for the other biomarkers. Glomerular filtration rate, proteinuria and treatment with statins or RAA axis antagonists were other independent correlates of the main outcome variables.

CONCLUSIONS

Our results support the hypothesis that urinary excretion rates of UA may represent a more accurate marker of UA-related kidney injury than plasma levels of this metabolite, in patients with advanced stages of CKD. Further, longitudinal studies will be necessary, to disclose the clinical significance of these findings.

Urinary Dickkopf 3 Is Not an Independent Risk Factor in a Cohort of Kidney Transplant Recipients and Living Donors

Urinary dickkopf 3 (uDKK3) is a marker released by kidney tubular epithelial cells that is associated with the progression of chronic kidney disease (CKD) and may cause interstitial fibrosis and tubular atrophy. Recent evidence suggests that uDKK3 can also predict the loss of kidney function in CKD patients and kidney transplant recipients, regardless of their current renal function. We conducted a prospective study on 181 kidney transplant (KTx) recipients who underwent allograft biopsy to determine the cause, analyzing the relationship between uDKK3 levels in urine, histological findings, and future allograft function progression. Additionally, we studied 82 living kidney donors before unilateral nephrectomy (Nx), 1-3 days after surgery, and 1 year post-surgery to observe the effects of rapid kidney function loss. In living donors, the uDKK3/creatinine ratio significantly increased 5.3-fold 1-3 days after Nx. However, it decreased significantly to a median level of 620 pg/mg after one year, despite the absence of underlying primary kidney pathology. The estimated glomerular filtration rate (eGFR) decreased by an average of 29.3% to approximately 66.5 (±13.5) mL/min/1.73 m2 after one year, with no further decline in the subsequent years. uDKK3 levels increased in line with eGFR loss after Nx, followed by a decrease as the eGFR partially recovered within the following year. However, uDKK3 did not correlate with the eGFR at the single time points in living donors. In KTx recipients, the uDKK3/creatinine ratio was significantly elevated with a median of 1550 pg/mg compared to healthy individuals or donors after Nx. The mean eGFR in the recipient group was 35.5 mL/min/1.73 m2. The uDKK3/creatinine ratio was statistically associated with the eGFR at biopsy but was not independently associated with the eGFR one year after biopsy or allograft loss. In conclusion, uDKK3 correlates with recent and future kidney function and kidney allograft survival in the renal transplant cohort. Nevertheless, our findings indicate that the uDKK3/creatinine ratio has no prognostic influence on future renal outcome in living donors and kidney recipients beyond the eGFR, independent of the presence of acute renal graft pathology, as correlations are GFR-dependent.

Association of Urinary Dickkopf-3 Levels with Cardiovascular Events and Kidney Disease Progression in Systolic Blood Pressure Intervention Trial

Key Points

In unadjusted analyses, elevated urinary Dickkopf-3 levels were strongly associated with higher risks of cardiovascular disease, ESKD, AKI, and mortality. However, associations were substantially weakened after adjustment for eGFR and albuminuria, suggesting limited prognostic value.

Background

Urinary Dickkopf-3 (uDKK3) is a tubular epithelial-derived profibrotic protein secreted into the urine under tubular stress. It is associated with kidney disease progression in persons with CKD and diabetes and postoperative and contrast-associated AKI. We explored associations of uDKK3 with cardiovascular disease (CVD), kidney, and mortality outcomes within the subset of Systolic Blood Pressure Intervention Trial participants with nondiabetic CKD.

Methods

We included 2344 participants with eGFR <60 ml/min per 1.73 m2 at baseline. We used Cox proportional hazards models to evaluate associations of uDKK3 with CVD (acute decompensated heart failure, myocardial infarction, acute coronary syndrome, stroke, or CVD death), kidney outcomes (incident ESKD, incident AKI, and eGFR decline ≥30%), and all-cause mortality. We used linear mixed models to examine the association of uDKK3 with annual percentage change in eGFR. Models were adjusted for demographic and clinical characteristics, eGFR, and albuminuria.

Results

Over a median follow-up of 3.5 years, there were 292 CVD, 73 ESKD, 183 AKI, 471 eGFR decline, and 228 mortality events. In multivariable models without adjustment for eGFR and albuminuria, uDKK3 was strongly associated with CVD, ESKD, AKI, eGFR decline ≥30%, and mortality. However, after further adjustment for eGFR and albuminuria, uDKK3 was no longer associated with risks for composite CVD (hazard ratio, 1.07; 95% confidence interval, 0.92 to 1.23), ESKD (0.80; 0.62 to 1.02), AKI (1.01; 0.85 to 1.21), eGFR decline ≥30% (0.88; 0.79 to 0.99), or mortality (1.02; 0.87 to 1.20). For the linear eGFR change outcome, higher uDKK3 also had no association in the fully adjusted model (−0.03; −0.41 to 0.36).

Conclusions

Among individuals with hypertension and nondiabetic CKD, higher uDKK3 appeared to have associations with a greater risk of CVD events, incident ESKD, incident AKI, eGFR decline ≥30%, and mortality but these associations were not independent of eGFR and albuminuria.

DKK3 promotes oxidative stress injury and fibrosis in HK-2 cells by activating NOX4 via β-catenin/TCF4 signaling

Oxidative stress and fibrosis may accelerate the progression of chronic kidney disease (CKD). DKK3 is related to regulating renal fibrosis and CKD. However, the molecular mechanism of DKK3 in regulating oxidative stress and fibrosis during CKD development has not been clarified, which deserves to be investigated. Human proximal tubule epithelial cells (HK-2 cells) were treated with H2O2 to establish a cell model of renal fibrosis. The mRNA and protein expressions were analyzed using qRT-PCR and western blot, respectively. Cell viability and apoptosis were evaluated using MTT assay and flow cytometry, respectively. ROS production was estimated using DCFH-DA. The interactions among TCF4, β-catenin and NOX4 were validated using luciferase activity assay, ChIP and Co-IP. Herein, our results revealed that DKK3 was highly expressed in HK-2 cells treated with H2O2. DKK3 depletion increased H2O2-treated HK-2 cell viability and reduced cell apoptosis, oxidative stress, and fibrosis. Mechanically, DKK3 promoted formation of the β-catenin/TCF4 complex, and activated NOX4 transcription. Upregulation of NOX4 or TCF4 weakened the inhibitory effect of DKK3 knockdown on oxidative stress and fibrosis in H2O2-stimulated HK-2 cells. All our results suggested that DKK3 accelerated oxidative stress and fibrosis through promoting β-catenin/TCF4 complex-mediated activation of NOX4 transcription, which could lead to novel molecules and therapeutic targets for CKD.

Prognostic Biomarkers and AKI: Potential to Enhance the Identification of Post-Operative Patients at Risk of Loss of Renal Function

Acute kidney injury (AKI) is a common complication after surgery and the more complex the surgery, the greater the risk. During surgery, patients are exposed to a combination of factors all of which are associated with the development of AKI. These include hypotension and hypovolaemia, sepsis, systemic inflammation, the use of nephrotoxic agents, tissue injury, the infusion of blood or blood products, ischaemia, oxidative stress and reperfusion injury. Given the risks of AKI, it would seem logical to conclude that early identification of patients at risk of AKI would translate into benefit. The conventional markers of AKI, namely serum creatinine and urine output are the mainstay of defining chronic kidney disease but are less suited to the acute phase. Such concerns are compounded in surgical patients given they often have significantly reduced mobility, suboptimal levels of nutrition and reduced muscle bulk. Many patients may also have misleadingly low serum creatinine and high urine output due to aggressive fluid resuscitation, particularly in intensive care units. Over the last two decades, considerable information has accrued with regard to the performance of what was termed "novel" biomarkers of AKI, and here, we discuss the most examined molecules and performance in surgical settings. We also discuss the application of biomarkers to guide patients' postoperative care.

Tissue fibrosis associated depletion of lipid-filled cells

Fibrosis is primarily described as the deposition of excessive extracellular matrix, but in many tissues it also involves a loss of lipid or lipid-filled cells. Lipid-filled cells are critical to tissue function and integrity in many tissues including the skin and lungs. Thus, loss or depletion of lipid-filled cells during fibrogenesis, has implications for tissue function. In some contexts, lipid-filled cells can impact ECM composition and stability, highlighting their importance in fibrotic transformation. Recent papers in fibrosis address this newly recognized fibrotic lipodystrophy phenomenon. Even in disparate tissues, common mechanisms are emerging to explain fibrotic lipodystrophy. These findings have implications for fibrosis in tissues composed of fibroblast and lipid-filled cell populations such as skin, lung, and liver. In this review, we will discuss the roles of lipid-containing cells, their reduction/loss during fibrotic transformation, and the mechanisms of that loss in the skin and lungs.

DKK3 as a potential novel biomarker in patients with autosomal polycystic kidney disease

Backgound

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease, and leads to a steady loss of kidney function in adulthood. The variable course of the disease makes it necessary to identify the patients with rapid disease progression who will benefit the most from targeted therapies and interventions. Currently, magnetic resonance imaging-based volumetry of the kidney is the most commonly used tool for this purpose. Biomarkers that can be easily and quantitatively determined, which allow a prediction of the loss of kidney function, have not yet been established in clinical practice. The glycoprotein Dickkopf 3 (DKK3) which is secreted in the renal tubular epithelium upon stress and contributes to tubulointerstitial fibrosis via the Wnt signaling pathway, was recently described as a biomarker for estimating risk of kidney function loss, but has not been investigated for ADPKD. This study aimed to obtain a first insight into whether DKK3 may indeed improve outcome prediction in ADPKD in the future.

Methods

In 184 ADPKD patients from the AD(H)PKD registry and 47 healthy controls, the urinary DKK3 (uDKK3) levels were determined using ELISA. Multiple linear regression was used to examine the potential of these values in outcome prediction.

Results

ADPKD patients showed significantly higher uDKK3 values compared with the controls (mean 1970 ± 5287 vs 112 ± 134.7 pg/mg creatinine). Furthermore, there was a steady increase in uDKK3 with an increase in the Mayo class (A/B 1262 ± 2315 vs class D/E 3104 ± 7627 pg/mg creatinine), the best-established biomarker of progression in ADPKD. uDKK3 also correlated with estimated glomerular filtration rate (eGFR). Patients with PKD1 mutations show higher uDKK3 levels compared with PKD2 patients (PKD1: 2304 ± 5119; PKD2: 506.6 ± 526.8 pg/mg creatinine). Univariate linear regression showed uDKK3 as a significant predictor of future eGFR slope estimation. In multiple linear regression this effect was not significant in models also containing height-adjusted total kidney volume and/or eGFR. However, adding both copeptin levels and the interaction term between copeptin and uDKK3 to the model resulted in a significant predictive value of all these three variables and the highest R2 of all models examined (∼0.5).

Conclusion

uDKK3 shows a clear correlation with the Mayo classification in patients with ADPKD. uDKK3 levels correlated with kidney function, which could indicate that uDKK3 also predicts a disproportionate loss of renal function in this collective. Interestingly, we found an interaction between copeptin and uDKK3 in our prediction models and the best model containing both variables and their interaction term resulted in a fairly good explanation of variance in eGFR slope compared with previous models. Considering the limited number of patients in these analyses, future studies will be required to confirm the results. Nonetheless, uDKK3 appears to be an attractive candidate to improve outcome prediction of ADPKD in the future.

New biomarkers in acute kidney injury

Acute kidney injury (AKI) is a commonly encountered clinical syndrome. Although it often complicates community acquired illness, it is more common in hospitalized patients, particularly those who are critically ill or who have undergone major surgery. Approximately 20% of hospitalized adult patients develop an AKI during their hospital care, and this rises to nearly 60% in the critically ill, depending on the population being considered. In general, AKI is more common in older adults, in those with preexisting chronic kidney disease and in those with known risk factors for AKI (including diabetes and hypertension). The development of AKI is associated with an increase in both mortality and morbidity, including the development of post-AKI chronic kidney disease. Currently, AKI is defined by a rise in serum creatinine from either a known or derived baseline value and/or oliguria or anuria. However, clinicians may fail to recognize the initial development of AKI because of a delay in the rise of serum creatinine or because of inaccurate urine output monitoring. This, in turn, delays any putative measures to treat AKI or to limit its degree. Consequently, efforts have focused on new biomarkers associated with AKI that may allow early recognition of this syndrome with the intent that this will translate into improved patient outcomes. Here we outline current biomarkers associated with AKI and explore their potential in aiding diagnosis, understanding the pathophysiology and directing therapy.

The role of urinary Dickkopf-3 in the prediction of acute kidney injury: a systematic review meta-analysis

BACKGROUND

To systematically evaluate the diagnostic efficacy of urinary Dickkopf-Related Protein 3 (DKK-3) in acute kidney injury and to explore the clinical application value of urinary DKK-3.

METHOD

English databases (PubMed, Embase, Cochrane, and WOS) and Chinese databases (VIP, WanFang data, and China National Knowledge Internet) were screened for relevant papers published before March 12, 2023. After literature screening and data extraction, quality assessment was performed according to the QUADAS-2 scoring system. Then, the combined diagnostic and predictive parameters were calculated using a bivariate mixed effect meta-analysis model. Deek's funnel plot asymmetry test assessed publication bias, and Fagan's nomogram plot was used to verify its clinical utility.

RESULT

A total of 5 studies involving 2787 patients were included in this meta-analysis, of which 4 focused on contrast-induced acute kidney injury (CI-AKI) and 1 focused on AKI associated with cardiac surgery. The analysis showed that urine Dickkopf-3 has high diagnostic accuracy for AKI, with a sensitivity of 0.55 (95% CI [0.41, 0.68]), specificity of 0.80 (95% CI [0.70, 0.87]), positive likelihood ratio (PLR) of 2.7 [1.8, 4.1], negative likelihood ratio (NLR) of 0.56 [0.42, 0.75], diagnostic odds ratio (DOR) of 5 [3, 9], and AUC of 0.74 [0.70-0.77]. We did not perform subgroup analyses for predictive value due to the small number of included studies.

CONCLUSION

Urinary DKK3 may have limited predictive ability for acute kidney injury, especially for AKI associated with cardiac surgery. Therefore, urinary DKK3 may serve as a potential predictor for AKI. However, clinical studies with larger samples are still needed for validation.

Kidney outcome after mild to moderate COVID-19

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a remarkable kidney tropism. While kidney effects are common in severe coronavirus disease 2019 (COVID-19), data on non-severe courses are limited. Here we provide a multilevel analysis of kidney outcomes after non-severe COVID-19 to test for eventual kidney sequela.

METHODS

This cross-sectional study investigates individuals after COVID-19 and matched controls recruited from the Hamburg City Health Study (HCHS) and its COVID-19 program. The HCHS is a prospective population-based cohort study within the city of Hamburg, Germany. During the COVID-19 pandemic the study additionally recruited subjects after polymerase chain reaction-confirmed SARS-CoV-2 infections. Matching was performed by age, sex and education. Main outcomes were estimated glomerular filtration rate (eGFR), albuminuria, Dickkopf3, haematuria and pyuria.

RESULTS

A total of 443 subjects in a median of 9 months after non-severe COVID-19 were compared with 1328 non-COVID-19 subjects. The mean eGFR was mildly lower in post-COVID-19 than non-COVID-19 subjects, even after adjusting for known risk factors {β = -1.84 [95% confidence interval (CI) -3.16 to -0.52]}. However, chronic kidney disease [odds ratio (OR) 0.90 (95% CI 0.48-1.66)] or severely increased albuminuria [OR 0.76 (95% CI 0.49-1.09)] equally occurred in post-COVID-19 and non-COVID-19 subjects. Haematuria, pyuria and proteinuria were also similar between the two cohorts, suggesting no ongoing kidney injury after non-severe COVID-19. Further, Dickkopf3 was not increased in the post-COVID-19 cohort, indicating no systematic risk for ongoing GFR decline [β = -72.19 (95% CI -130.0 to -14.4)].

CONCLUSION

While mean eGFR was slightly lower in subjects after non-severe COVID-19, there was no evidence for ongoing or progressive kidney sequela.

Validated graft-specific biomarkers identify patients at risk for chronic graft-versus-host disease and death

BACKGROUNDChronic graft-versus-host disease (cGVHD) is a serious complication of allogeneic hematopoietic cell transplantation (HCT). More accurate information regarding the risk of developing cGVHD is required. Bone marrow (BM) grafts contribute to lower cGVHD, which creates a dispute over whether risk biomarker scores should be used for peripheral blood (PB) and BM.METHODSDay 90 plasma proteomics from PB and BM recipients developing cGVHD revealed 5 risk markers that were added to 8 previous cGVHD markers to screen 982 HCT samples of 2 multicenter Blood and Marrow Transplant Clinical Trials Network (BMTCTN) cohorts. Each marker was tested for its association with cause-specific hazard ratios (HRs) of cGVHD using Cox-proportional-hazards models. We paired these clinical studies with biomarker measurements in a mouse model of cGVHD.RESULTSSpearman correlations between DKK3 and MMP3 were significant in both cohorts. In BMTCTN 0201 multivariate analyses, PB recipients with 1-log increase in CXCL9 and DKK3 were 1.3 times (95% CI: 1.1-1.4, P = 0.001) and 1.9 times (95%CI: 1.1-3.2, P = 0.019) and BM recipients with 1-log increase in CXCL10 and MMP3 were 1.3 times (95%CI: 1.0-1.6, P = 0.018 and P = 0.023) more likely to develop cGVHD. In BMTCTN 1202, PB patients with high CXCL9 and MMP3 were 1.1 times (95%CI: 1.0-1.2, P = 0.037) and 1.2 times (95%CI: 1.0-1.3, P = 0.009) more likely to develop cGVHD. PB patients with high biomarkers had increased likelihood to develop cGVHD in both cohorts (22%-32% versus 8%-12%, P = 0.002 and P < 0.001, respectively). Mice showed elevated circulating biomarkers before the signs of cGVHD.CONCLUSIONBiomarker levels at 3 months after HCT identify patients at risk for cGVHD occurrence.FUNDINGNIH grants R01CA168814, R21HL139934, P01CA158505, T32AI007313, and R01CA264921.

Patterns of Dickkopf-3 Serum and Urine Levels at Different Stages of Chronic Kidney Disease

Dickkopf 3 (Dkk3) is a WNT/β-catenin signaling pathway regulator secreted by tubular epithelial cells upon the influence of different stressors. Recently Dkk3 was described as a biomarker of tubular cell injury and a tool that may estimate the risk of chronic kidney disease (CKD) progression. The data about Dkk3 concentrations at particular stages of CKD are lacking. The aim of this study was to measure serum and urine Dkk3 levels in patients with different 'renal status' and evaluate its role as a biomarker of renal damage. One hundred individuals, aged between 24 and 85 years (mean 53.1 ± 17.1), were enrolled in the study. Five groups of 20 subjects each were recruited based on their kidney function. Serum and urine Dkk3 levels were measured by ELISA. The highest median urinary Dkk3 normalized to urinary creatinine was found in patients with established CKD (7051 pg/mg). It was two times higher in renal transplant patients (5705 pg/mg) than in healthy individuals (2654 pg/mg) and the glomerulonephritis group (2470 pg/mg). Urinary Dkk3 was associated with serum creatinine in participants with established CKD and following transplantation. Our results confirm the potential role of Dkk3 as a biomarker of an ongoing renal injury.

Recent Advances in Urinary Peptide and Proteomic Biomarkers in Chronic Kidney Disease: A Systematic Review

Biomarker development, improvement, and clinical implementation in the context of kidney disease have been a central focus of biomedical research for decades. To this point, only serum creatinine and urinary albumin excretion are well-accepted biomarkers in kidney disease. With their known blind spot in the early stages of kidney impairment and their diagnostic limitations, there is a need for better and more specific biomarkers. With the rise in large-scale analyses of the thousands of peptides in serum or urine samples using mass spectrometry techniques, hopes for biomarker development are high. Advances in proteomic research have led to the discovery of an increasing amount of potential proteomic biomarkers and the identification of candidate biomarkers for clinical implementation in the context of kidney disease management. In this review that strictly follows the PRISMA guidelines, we focus on urinary peptide and especially peptidomic biomarkers emerging from recent research and underline the role of those with the highest potential for clinical implementation. The Web of Science database (all databases) was searched on 17 October 2022, using the search terms "marker *" OR biomarker * AND "renal disease" OR "kidney disease" AND "proteome *" OR "peptid *" AND "urin *". English, full-text, original articles on humans published within the last 5 years were included, which had been cited at least five times per year. Studies based on animal models, renal transplant studies, metabolite studies, studies on miRNA, and studies on exosomal vesicles were excluded, focusing on urinary peptide biomarkers. The described search led to the identification of 3668 articles and the application of inclusion and exclusion criteria, as well as abstract and consecutive full-text analyses of three independent authors to reach a final number of 62 studies for this manuscript. The 62 manuscripts encompassed eight established single peptide biomarkers and several proteomic classifiers, including CKD273 and IgAN237. This review provides a summary of the recent evidence on single peptide urinary biomarkers in CKD, while emphasizing the increasing role of proteomic biomarker research with new research on established and new proteomic biomarkers. Lessons learned from the last 5 years in this review might encourage future studies, hopefully resulting in the routine clinical applicability of new biomarkers.

Prediction of urinary dickkopf-3 for AKI, sepsis-associated AKI, and PICU mortality in children

BACKGROUND

Preoperative urinary dickkopf-3 (DKK3) is proposed as an early biomarker for the prediction of acute kidney injury (AKI) in patients undergoing cardiac surgery. We explored the clinical utility of urinary DKK3 for the early predictive value for AKI, sepsis-associated AKI (SA-AKI), and pediatric intensive care unit (PICU) mortality in critically ill children.

METHODS

Urine samples were collected during the first 24 h after admission for measurement of DKK3. AKI diagnosis was based on serum creatinine and urine output using the KDIGO criteria. SA-AKI was defined as AKI that occurred in children who met the sepsis criteria in accordance with the surviving sepsis campaign international guidelines for children.

RESULTS

Of the 420 children, 73 developed AKI, including 24 with SA-AKI, and 30 died during the PICU stay. The urinary DKK3 level was significantly associated with AKI, SA-AKI, and PICU mortality, even after adjustment for confounders. The area under the receiver operating characteristic curve of urinary DKK3 for the discrimination of AKI, SA-AKI, and PICU mortality was 0.70, 0.80, and 0.78, respectively.

CONCLUSION

Urinary DKK3 was independently associated with an increased risk for AKI, SA-AKI, and PICU mortality and may be predictive of the aforementioned issues in critically ill children.

IMPACT

Urinary dickkopf-3 (DKK3) has been identified as a preoperative biomarker for the prediction of acute kidney injury (AKI) following cardiac surgery or coronary angiography in adult patients. However, little is known about the clinical utility of urinary DKK3 in pediatric cohorts. This study demonstrated that urinary DKK3 is capable of early predicting AKI and pediatric intensive care unit (PICU) mortality and discriminating sepsis-associated AKI (SA-AKI) from other types of AKI. Urinary DKK3 may be an early biomarker for predicting AKI, SA-AKI, and PICU mortality in critically ill children.

Urinary DKK3 as a biomarker for short-term kidney function decline in children with chronic kidney disease: an observational cohort study

BACKGROUND

Childhood-onset chronic kidney disease is a progressive condition that can have a major effect on life expectancy and quality. We evaluated the usefulness of the kidney tubular cell stress marker urinary Dickkopf-related protein 3 (DKK3) in determining the short-term risk of chronic kidney disease progression in children and identifying those who will benefit from specific nephroprotective interventions.

METHODS

In this observational cohort study, we assessed the association between urinary DKK3 and the combined kidney endpoint (ie, the composite of 50% reduction of the estimated glomerular filtration rate [eGFR] or progression to end-stage kidney disease) or the risk of kidney replacement therapy (ie, dialysis or transplantation), and the interaction of the combined kidney endpoint with intensified blood pressure reduction in the randomised controlled ESCAPE trial. Moreover, urinary DKK3 and eGFR were quantified in children aged 3-18 years with chronic kidney disease and urine samples available enrolled in the prospective multicentre ESCAPE (NCT00221845; derivation cohort) and 4C (NCT01046448; validation cohort) studies at baseline and at 6-monthly follow-up visits. Analyses were adjusted for age, sex, hypertension, systolic blood pressure SD score (SDS), BMI SDS, albuminuria, and eGFR.

FINDINGS

659 children were included in the analysis (231 from ESCAPE and 428 from 4C), with 1173 half-year blocks in ESCAPE and 2762 in 4C. In both cohorts, urinary DKK3 above the median (ie, >1689 pg/mg creatinine) was associated with significantly greater 6-month eGFR decline than with urinary DKK3 at or below the median (-5·6% [95% CI -8·6 to -2·7] vs 1·0% [-1·9 to 3·9], p<0·0001, in ESCAPE; -6·2% [-7·3 to -5·0] vs -1·5% [-2·9 to -0·1], p<0·0001, in 4C), independently of diagnosis, eGFR, and albuminuria. In ESCAPE, the beneficial effect of intensified blood pressure control was limited to children with urinary DKK3 higher than 1689 pg/mg creatinine, in terms of the combined kidney endpoint (HR 0·27 [95% CI 0·14 to 0·55], p=0·0003, number needed to treat 4·0 [95% CI 3·7 to 4·4] vs 250·0 [66·9 to ∞]) and the need for kidney replacement therapy (HR 0·33 [0·13 to 0·85], p=0·021, number needed to treat 6·7 [6·1 to 7·2] vs 31·0 [27·4 to 35·9]). In 4C, inhibition of the renin-angiotensin-aldosterone system resulted in significantly lower urinary DKK3 concentrations (least-squares mean 12 235 pg/mg creatinine [95% CI 10 036 to 14 433] in patients not on angiotensin-converting enzyme inhibitors or angiotensin 2 receptor blockers vs 6861 pg/mg creatinine [5616 to 8106] in those taking angiotensin-converting enzyme inhibitors or angiotensin 2 receptor blockers, p<0·0001).

INTERPRETATION

Urinary DKK3 indicates short-term risk of declining kidney function in children with chronic kidney disease and might allow a personalised medicine approach by identifying those who benefit from pharmacological nephroprotection, such as intensified blood pressure lowering.

FUNDING

None.

Biomarkers of fibrosis, kidney tissue injury and inflammation may predict severity and outcome of renal ANCA – associated vasculitis

Background

Activity and chronicity of kidney involvement in ANCA-associated vasculitis (AAV) can be currently reliably evaluated only by kidney biopsy. In this study, we measured a panel of serum and urinary biomarkers collected at the time of kidney biopsy and hypothesized that they could reflect specific histopathological parameters in the biopsy and help to predict prognosis.

Methods

We examined a cohort of 45 patients with AAV and 10 healthy controls. Biomarker levels (DKK-3, CD163, EGF, PRO-C6 and C3M) were measured in this study by ELISA. Biopsies were scored with a scoring system for AAV (focal x crescentic x sclerotic x mixed class) and interstitial fibrosis was quantified.

Results

Levels of urinary DKK-3, CD163, EGF, PRO-C6 and C3M significantly differed among biopsy classes in AAV, with urinary DKK-3 and PRO-C6 levels being highest in the sclerotic class and lowest in the focal class, urinary CD163 levels highest in the crescentic class and urinary C3M levels highest in the focal class. Moreover, the urinary biomarkers were able to discriminate focal biopsy class from the other classes. Urinary DKK-3, EGF, PRO-C6 and C3M levels measured at the time of biopsy were also significantly related to the extent of fibrosis and to the final kidney function at the end of follow-up.

Conclusions

This small pilot study suggests that selected urinary biomarkers of fibrosis and inflammation may reflect changes in the kidney biopsy and be prognostic of kidney outcome in patients with AAV.

Urinary Dickkopf-3 (DKK3) Is Associated with Greater eGFR Loss in Patients with Resistant Hypertension

Patients with resistant hypertension (HTN) demonstrate an increased risk of chronic kidney disease and progression to end-stage renal disease; however, the individual course of progression is hard to predict. Assessing the stress-induced, urinary glycoprotein Dickkopf-3 (uDKK3) may indicate ongoing renal damage and consecutive estimated glomerular filtration rate (eGFR) decline. The present study aimed to determine the association between uDKK3 levels and further eGFR changes in patients with resistant HTN. In total, 31 patients with resistant HTN were included. Blood pressure and renal function were measured at baseline and up to 24 months after (at months 12 and 24). uDKK3 levels were determined exclusively from the first available spot urine sample at baseline or up to a period of 6 months after, using a commercial ELISA kit. Distinctions between different patient groups were analyzed using the unpaired t-test or Mann-Whitney test. Correlation analysis was performed using Spearman's correlation. The median uDKK3 level was 303 (interquartile range (IQR) 150-865) pg/mg creatinine. Patients were divided into those with high and low eGFR loss (≥3 vs. <3 mL/min/1.73 m²/year). Patients with high eGFR loss showed a significantly higher median baseline uDKK3 level (646 (IQR 249-2555) (n = 13) vs. 180 (IQR 123-365) pg/mg creatinine (n = 18), p = 0.0412 (Mann-Whitney U)). Alternatively, patients could be classified into those with high and low uDKK3 levels (≥400 vs. <400 pg/mg creatinine). Patients with high uDKK3 levels showed significantly higher eGFR loss (-6.4 ± 4.7 (n = 11) vs. 0.0 ± 7.6 mL/min/1.73 m²/year (n = 20), p = 0.0172 (2-sided, independent t-test)). Within the entire cohort, there was a significant correlation between the uDKK3 levels and change in eGFR at the latest follow-up (Spearman's r = -0.3714, p = 0.0397). In patients with resistant HTN, high levels of uDKK3 are associated with higher eGFR loss up to 24 months later.

Dickkopf-3: An Update on a Potential Regulator of the Tumor Microenvironment

Dickkopf-3 (Dkk-3) is a member of the Dickkopf family protein of secreted Wingless-related integration site (Wnt) antagonists that appears to modulate regulators of the host microenvironment. In contrast to the clear anti-tumorigenic effects of Dkk-3-based gene therapies, the role of endogenous Dkk-3 in cancer is context-dependent, with elevated expression associated with tumor promotion and suppression in different settings. The receptors and effectors that mediate the diverse effects of Dkk-3 have not been characterized in detail, contributing to an ongoing mystery of its mechanism of action. This review compares the various functions of Dkk-3 in the tumor microenvironment, where Dkk-3 has been found to be expressed by subpopulations of fibroblasts, endothelial, and immune cells, in addition to epithelial cells. We also discuss how the activation or inhibition of Dkk-3, depending on tumor type and context, might be used to treat different types of cancers.

Advances in laboratory detection of acute kidney injury

Recent advances have improved our understanding of the epidemiology and pathophysiology of acute kidney injury (AKI). So far, the Kidney Disease: Improving Global Outcome guidelines define and stratify kidney injury based on increases in serum creatinine level and/or decreases in urine output. Although the term AKI acknowledges the existence of cellular injury, its diagnosis is still only defined by the reduced excretory function of the kidney. New biomarkers that aid a better understanding of the relationship between acute tubular injury and kidney dysfunction have been identified, reflecting the advances in molecular biology. The expression of some of these novel biomarkers precedes changes in conventional biomarkers or can increase their predictive power. Therefore, they might enhance the clinical accuracy of the definition of AKI. This review summarizes the limitations of the current AKI classification and a panel of candidate biomarkers for augmenting AKI classification and recognition of AKI subphenotypes. We expect that the integration of appropriately selected biomarkers in routine clinical practice can improve AKI care.

Dickkopf 3-A New Indicator for the Deterioration of Allograft Function After Kidney Transplantation

Evidence of tubular atrophy and interstitial fibrosis is prognostically unfavorable and associated with a premature graft loss after kidney transplantation. Recently, Dickkopf 3 (DKK3), a profibrotic glycoprotein released by stressed tubular epithelial cells, has been identified to cause IF/TA by regulating the Wnt/β-catenin signaling and seems to engage a T-cell response. The aim of our study was to determine if a correlation between DKK3 and graft function exists and if DKK3 could be a new indicator to identify patients at risk for a deterioration in graft function. Patients, transplanted between 2016 and 2018, were analyzed with regard to DKK3 in the urine and graft function (creatinine, eGFR, albuminuria). Multivariable analyzes were used including known factors influencing graft function (PRA, donor age) to stress robustness of DKK3. The 3 and 12 month DKK3 values were significant predictors for subsequent graft function up to 36 months. An increase of DKK3 from month 3 to 12 of ≥ 25% showed a higher risk of an impaired graft function, with, e.g., a reduction in eGFR of about 9–10 ml/min in contrast to patients without intensified DKK3 increase. Induction therapy has an influence on DKK3 as patients induced with a T-cell depleting therapy showed a trend toward lower DKK3 values. In summary, our study is the first investigation of DKK3 in kidney transplant recipients and was able to show that DKK3 could forecast graft function. It is recommended to investigate the potential of DKK3 as a predictor of kidney function after transplantation in further studies.

Endotrophin, a collagen type VI-derived matrikine, reflects the degree of renal fibrosis in patients with IgA nephropathy and in patients with ANCA-associated vasculitis

BACKGROUND

Renal fibrosis is the hallmark of chronic kidney disease (CKD) and is characterized by an imbalanced extracellular matrix remodelling. Endotrophin (ETP) is a signalling molecule released from collagen type VI (COL VI). ETP can be measured by the PRO-C6 assay, which quantifies the levels of COL VI formation. ETP levels were previously associated with mortality and disease progression in patients with CKD. We hypothesized that serum and urinary ETP levels correlate with the degree of interstitial fibrosis in kidney biopsies from patients with immunoglobulin A nephropathy (IgAN) and patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

We examined a cohort of 49 IgAN and 47 AAV patients. A validation cohort of 85 IgAN patients was included. ETP was measured in serum (S-ETP) and urine (U-ETP/Cr) samples, taken on the same day before renal biopsy was performed, using the enzyme-linked immunosorbent assay PRO-C6. The biopsies were evaluated for interstitial fibrosis and tubular atrophy according to the Banff and MEST-C scores.

RESULTS

S-ETP and U-ETP/Cr levels correlated with kidney function, increased CKD severity, correlated with the extent of interstitial fibrosis and gradually increased with increasing degree of interstitial fibrosis and tubular atrophy. ETP outperformed the known fibrosis biomarker Dickkopf-3 for discrimination of patients with high fibrotic burden. The association of S-ETP and U-ETP/Cr with the level of kidney fibrosis was confirmed in the validation cohort.

CONCLUSIONS

We demonstrated that high levels of circulating and excreted ETP are not only indicative of lower kidney function, but also reflect the burden of fibrosis in the kidneys.

Usefulness of urinary biomarkers to estimate the interstitial fibrosis surface in diabetic nephropathy with normal kidney function

BACKGROUND

Kidney biopsies of patients with diabetic nephropathy (DN) and normal kidney function may exhibit interstitial fibrosis (IF) without reduction of glomerular filtration rate because of hyperfiltration. The aim of our study was to analyze the performance of a set of biomarkers of tubular injury to estimate the extent of IF in patients with DN and normal kidney function.

PATIENTS AND METHODS

This cross-sectional study included 118 adults with DN diagnosed by kidney biopsy and GFR ≥ 90 mL/min/1.73 m2 and a control group of healthy subjects. We measured the urinary excretion of MCP-1, NGAL, KIM-1, L-FABP, β2-microglobulin and DKK-3 at the time of kidney biopsy. GFR was measured by Cr-EDTA (mGFR). IF was quantified using a quantitative morphometric procedure. Predictive multivariate models were developed to estimate the IF surface.

RESULTS

patients with DN showed significantly higher levels of DKK-3, MCP-1 and L-FABP and significantly lower levels of EGF than healthy controls. There were no significant between-group differences in the levels of β2-microglobulin, KIM-1 or NGAL. IF was negatively associated with EGF and a positively with age, proteinuria, MCP-1, DKK-3 and L-FABP but no with β2-microglobulin, KIM-1, NGAL or GFR. The best model to predict IF surface accounted for 59% of its variability and included age, proteinuria, EGF, DKK-3 and MCP-1.

CONCLUSIONS

our study provides a model to estimate the IF in DN that can be useful to assess the progression of IF in patients with normal kidney function.

Fibrotic Signaling in Cardiac Fibroblasts and Vascular Smooth Muscle Cells: The Dual Roles of Fibrosis in HFpEF and CAD

Patients with heart failure with preserved ejection fraction (HFpEF) and atherosclerosis-driven coronary artery disease (CAD) will have ongoing fibrotic remodeling both in the myocardium and in atherosclerotic plaques. However, the functional consequences of fibrosis differ for each location. Thus, cardiac fibrosis leads to myocardial stiffening, thereby compromising cardiac function, while fibrotic remodeling stabilizes the atherosclerotic plaque, thereby reducing the risk of plaque rupture. Although there are currently no drugs targeting cardiac fibrosis, it is a field under intense investigation, and future drugs must take these considerations into account. To explore similarities and differences of fibrotic remodeling at these two locations of the heart, we review the signaling pathways that are activated in the main extracellular matrix (ECM)-producing cells, namely human cardiac fibroblasts (CFs) and vascular smooth muscle cells (VSMCs). Although these signaling pathways are highly overlapping and context-dependent, effects on ECM remodeling mainly act through two core signaling cascades: TGF-β and Angiotensin II. We complete this by summarizing the knowledge gained from clinical trials targeting these two central fibrotic pathways.

Study on the Action Mechanism of Dkk-1, TGF-β1 and TNF-α Expression Levels in Dupuytren's Contracture

BACKGROUND

The biological mechanism of Dupuytren's contracture needs to be further studied in order to minimize postoperative recurrence and provide a pathological basis for the development of new therapeutic targets.

METHODS

HE staining, immunohistochemistry, PCR and western blotting were performed in pathological palmar aponeurosis specimens and normal palmar aponeurosis tissues for comparative study.

RESULTS

(1) TNF-α expression was up-regulated: TNF-α mRNA was more highly expressed in the pathological tissues of DD patients than in the CT group, P < 0.05, and the difference between the two groups was statistically significant; (2) Dkk-1 expression was down-regulated: Dkk-1 mRNA was lower expressed in the pathological tissues of DD patients than in the CT group, P < 0.05, and the difference between the two groups was statistically significant; (3) TGF-β1 expression was up-regulated: TGF-β1 mRNA was higher expressed in the pathological tissues of DD patients than in the CT group, P < 0.05, and the difference between the two groups was statistically significant; (4) Pearson correlation analysis suggested that TNF-α expression was positively correlated with TGF-β1 expression, TNF-α expression was negatively correlated with DKK-1 expression, and TGF-β1 expression was negatively correlated with DKK-1 expression.

CONCLUSION

TNF-α, DKK-1 and TGF-β1 may play a role in the pathogenesis of palmar aponeurosis contracture, and there is a relationship between them. The study of the relationship between the three and their related signaling pathways provides a therapeutic target and a basis for the prevention and early treatment of palmar aponeurotic contracture.

Dickkopf proteins in pathological inflammatory diseases

The human body encounters various challenges. Tissue repair and regeneration processes are augmented after tissue injury to reinstate tissue homeostasis. The Wnt pathway plays a crucial role in tissue repair since it induces target genes required for cell proliferation and differentiation. Since tissue injury causes inflammatory immune responses, it has become increasingly clear that the Wnt ligands can function as immunomodulators while critical for tissue homeostasis. The Wnt pathway and Wnt ligands have been studied extensively in cancer biology and developmental biology. While the Wnt ligands are being studied actively, how the Wnt antagonists and their regulatory mechanisms can modulate immune responses during chronic pathological inflammation remain elusive. This review summarizes DKK family proteins as immunomodulators, aiming to provide an overarching picture for tissue injury and repair. To this end, we first review the Wnt pathway components and DKK family proteins. Next, we will review DKK family proteins (DKK1, 2, and 3) as a new class of immunomodulatory protein in cancer and other chronic inflammatory diseases. Taken together, DKK family proteins and their immunomodulatory functions in chronic inflammatory disorders provide novel insights to understand immune diseases and make them attractive molecular targets for therapeutic intervention.

miR-25-3p protects renal tubular epithelial cells from apoptosis induced by renal IRI by targeting DKK3

Renal ischemia-reperfusion injury (IRI) is one of the main causes of acute kidney injury (AKI). So far, there have been many studies on renal IRI, although an effective treatment method has not been developed. In recent years, growing evidence has shown that small noncoding RNAs play an important regulatory role in renal IRI. This article aims to explore whether microRNA-25-3p (miR-25-3p) plays a role in the molecular mechanism of renal IRI. The results showed that the expression level of miR-25-3p was significantly downregulated in a rat renal IRI model, and this result was confirmed with in vitro experiments. After the hypoxia-reoxygenation treatment, the apoptosis level of NRK-52E cells transfected with miR-25-3p mimics decreased significantly, and this antiapoptotic effect was antagonized by miR-25-3p inhibitors. In addition, we confirmed that DKK3 is a target of miR-25-3p. miR-25-3p exerts its protective effect against apoptosis on NRK-52E cells by inhibiting the expression of DKK3, and downregulating the expression level of miR-25-3p could disrupt this protective effect. In addition, we reconfirmed the role of miR-25-3p in rats. Therefore, we confirmed that miR-25-3p may target DKK3 to reduce renal cell damage caused by hypoxia and that miR-25-3p may be a new potential treatment for renal IRI.

Advances in the Progression and Prognosis Biomarkers of Chronic Kidney Disease

Chronic kidney disease (CKD) is one of the increasingly serious public health concerns worldwide; the global burden of CKD is increasingly due to high morbidity and mortality. At present, there are three key problems in the clinical treatment and management of CKD. First, the current diagnostic indicators, such as proteinuria and serum creatinine, are greatly interfered by the physiological conditions of patients, and the changes in the indicator level are not synchronized with renal damage. Second, the established diagnosis of suspected CKD still depends on biopsy, which is not suitable for contraindication patients, is also traumatic, and is not sensitive to early progression. Finally, the prognosis of CKD is affected by many factors; hence, it is ineviatble to develop effective biomarkers to predict CKD prognosis and improve the prognosis through early intervention. Accurate progression monitoring and prognosis improvement of CKD are extremely significant for improving the clinical treatment and management of CKD and reducing the social burden. Therefore, biomarkers reported in recent years, which could play important roles in accurate progression monitoring and prognosis improvement of CKD, were concluded and highlighted in this review article that aims to provide a reference for both the construction of CKD precision therapy system and the pharmaceutical research and development.

Urinary Dickkopf-3 and kidney injury in patients with chronic pulmonary disease

Dickkopf-related protein 3 is a stress-induced, epithelial cell-derived glycoprotein that is promoted as a prognostic as well as a predictive urinary biomarker in acute and chronic kidney disease. Schunk et al. provided evidence that Dickkopf-related protein 3 identifies patients with chronic obstructive pulmonary disease and preserved kidney function at increased risk for a loss of estimated glomerular filtration rate and deterioration of pulmonary function. Experimental data highlighted Dickkopf-related protein 3-related pathophysiological similarities and interactions between chronic kidney disease and chronic obstructive pulmonary disease.

Functional Characterization of Organoids Derived From Irreversibly Damaged Liver of Patients With NASH

BACKGROUND AND AIMS

NASH will soon become the leading cause of liver transplantation in the United States and is also associated with increased COVID-19 mortality. Currently, there are no Food and Drug Administration-approved drugs available that slow NASH progression or address NASH liver involvement in COVID-19. Because animal models cannot fully recapitulate human NASH, we hypothesized that stem cells isolated directly from end-stage liver from patients with NASH may address current knowledge gaps in human NASH pathology.

APPROACH AND RESULTS

We devised methods that allow the derivation, proliferation, hepatic differentiation, and extensive characterization of bipotent ductal organoids from irreversibly damaged liver from patients with NASH. The transcriptomes of organoids derived from NASH liver, but not healthy liver, show significant up-regulation of proinflammatory and cytochrome p450-related pathways, as well as of known liver fibrosis and tumor markers, with the degree of up-regulation being patient-specific. Functionally, NASH liver organoids exhibit reduced passaging/growth capacity and hallmarks of NASH liver, including decreased albumin production, increased free fatty acid-induced lipid accumulation, increased sensitivity to apoptotic stimuli, and increased cytochrome P450 metabolism. After hepatic differentiation, NASH liver organoids exhibit reduced ability to dedifferentiate back to the biliary state, consistent with the known reduced regenerative ability of NASH livers. Intriguingly, NASH liver organoids also show strongly increased permissiveness to severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) vesicular stomatitis pseudovirus as well as up-regulation of ubiquitin D, a known inhibitor of the antiviral interferon host response.

CONCLUSION

Expansion of primary liver stem cells/organoids derived directly from irreversibly damaged liver from patients with NASH opens up experimental avenues for personalized disease modeling and drug development that has the potential to slow human NASH progression and to counteract NASH-related SARS-CoV-2 effects.

Targeting the Wnt/β-Catenin Signaling Pathway as a Potential Therapeutic Strategy in Renal Tubulointerstitial Fibrosis

The Wnt/β-catenin signaling pathway plays important roles in embryonic development and tissue homeostasis. Wnt signaling is induced, and β-catenin is activated, associated with the development and progression of renal fibrosis. Wnt/β-catenin controls the expression of various downstream mediators such as snail1, twist, matrix metalloproteinase-7, plasminogen activator inhibitor-1, transient receptor potential canonical 6, and renin-angiotensin system components in epithelial cells, fibroblast, and macrophages. In addition, Wnt/β-catenin is usually intertwined with other signaling pathways to promote renal interstitial fibrosis. Actually, given the crucial of Wnt/β-catenin signaling in renal fibrogenesis, blocking this signaling may benefit renal interstitial fibrosis. There are several antagonists of Wnt signaling that negatively control Wnt activation, and these include soluble Fzd-related proteins, the family of Dickkopf 1 proteins, Klotho and Wnt inhibitory factor-1. Furthermore, numerous emerging small-molecule β-catenin inhibitors cannot be ignored to prevent and treat renal fibrosis. Moreover, we reviewed the knowledge focusing on anti-fibrotic effects of natural products commonly used in kidney disease by inhibiting the Wnt/β-catenin signaling pathway. Therefore, in this review, we summarize recent advances in the regulation, downstream targets, role, and mechanisms of Wnt/β-catenin signaling in renal fibrosis pathogenesis. We also discuss the therapeutic potential of targeting this pathway to treat renal fibrosis; this may shed new insights into effective treatment strategies to prevent and treat renal fibrosis.

Renal markers for monitoring acute kidney injury transition to chronic kidney disease after COVID-19

URL http://www.clinicaltrials.gov. Unique identifier: NCT04353583.

Transcriptome Analysis of Differentially Expressed mRNA Related to Pigeon Muscle Development

The mechanisms behind the gene expression and regulation that modulate the development and growth of pigeon skeletal muscle remain largely unknown. In this study, we performed gene expression analysis on skeletal muscle samples at different developmental and growth stages using RNA sequencing (RNA-Seq). The differentially expressed genes (DEGs) were identified using edgeR software. Weighted gene co-expression network analysis (WGCNA) was used to identify the gene modules related to the growth and development of pigeon skeletal muscle based on DEGs. A total of 11,311 DEGs were identified. WGCNA aggregated 11,311 DEGs into 12 modules. Black and brown modules were significantly correlated with the 1st and 10th day of skeletal muscle growth, while turquoise and cyan modules were significantly correlated with the 8th and 13th days of skeletal muscle embryonic development. Four mRNA-mRNA regulatory networks corresponding to the four significant modules were constructed and visualised using Cytoscape software. Twenty candidate mRNAs were identified based on their connectivity degrees in the networks, including Abca8b, TCONS-00004461, VWF, OGDH, TGIF1, DKK3, Gfpt1 and RFC5, etc. A KEGG pathway enrichment analysis showed that many pathways were related to the growth and development of pigeon skeletal muscle, including PI3K/AKT/mTOR, AMPK, FAK, and thyroid hormone pathways. Five differentially expressed genes (LAST2, MYPN, DKK3, B4GALT6 and OGDH) in the network were selected, and their expression patterns were quantified by qRT-PCR. The results were consistent with our sequencing results. These findings could enhance our understanding of the gene expression and regulation in the development and growth of pigeon muscle.

Dickkopf 3-a novel biomarker of the 'kidney injury continuum'

Chronic kidney disease (CKD) is a global public health problem accompanied by substantial comorbidities and reduced life expectancy. In this respect, progressive CKD leading to uraemia can be seen as a systemic disease with a critical impact on virtually all organ systems. Therefore, it is of particular importance to identify patients with ongoing CKD progression, which is challenging, because the individual course of CKD is difficult to predict. Patterns of progression in CKD patients include linear and non-linear trajectories of GFR loss, but kidney function can also remain stable for years. Moreover, a substantial GFR decline may occur in the absence of higher-grade albuminuria (non-proteinuric CKD), rendering the measurement of albuminuria less reliable for progression prediction in such individuals. In the present review, we focus on the recently identified glycoprotein Dickkopf-3 (DKK3) as a stress-induced, renal tubular epithelial cell-derived, pro-fibrotic molecule. In experimental CKD models, DKK3 promoted renal tubulointerstitial fibrosis through modulation of the canonical Wnt/β-catenin signalling pathway. In clinical studies, increased urinary DKK3 levels identified patients at high risk for short-term CKD progression, regardless of the cause of kidney disease, baseline kidney function and albuminuria. Moreover, increased urinary DKK3 levels are associated with a high risk for acute kidney injury and the subsequent loss of kidney function after cardiac surgery. These findings highlight DKK3 as a mediator of renal tubular cell damage in kidney injury and short-term progression of kidney disease, with potential therapeutic implications.

Measurement of urinary Dickkopf-3 uncovered silent progressive kidney injury in patients with chronic obstructive pulmonary disease

Chronic kidney disease (CKD) represents a global public health problem with high disease related morbidity and mortality. Since CKD etiology is heterogeneous, early recognition of patients at risk for progressive kidney injury is important. Here, we evaluated the tubular epithelial derived glycoprotein dickkopf-3 (DKK3) as a urinary marker for the identification of progressive kidney injury in a non-CKD cohort of patients with chronic obstructive pulmonary disease (COPD) and in an experimental model. In COSYCONET, a prospective multicenter trial comprising 2,314 patients with stable COPD (follow-up 37.1 months), baseline urinary DKK3, proteinuria and estimated glomerular filtration rate (eGFR) were tested for their association with the risk of declining eGFR and the COPD marker, forced expiratory volume in one second. Baseline urinary DKK3 but not proteinuria or eGFR identified patients with a significantly higher risk for over a 10% (odds ratio: 1.54, 95% confidence interval: 1.13-2.08) and over a 20% (2.59: 1.28-5.25) decline of eGFR during follow-up. In particular, DKK3 was associated with a significantly higher risk for declining eGFR in patients with eGFR over 90 ml/min/1.73m² and proteinuria under 30 mg/g. DKK3 was also associated with declining COPD marker (2.90: 1.70-4.68). The impact of DKK3 was further explored in wild-type and Dkk3-/- mice subjected to cigarette smoke-induced lung injury combined with a CKD model. In this model, genetic abrogation of DKK3 resulted in reduced pulmonary inflammation and preserved kidney function. Thus, our data highlight urinary DKK3 as a possible marker for early identification of patients with silent progressive CKD and for adverse outcomes in patients with COPD.

Precision medicine in diabetic nephropathy and chronic kidney disease

Progressive chronic kidney disease (CKD) in individuals with type 2 diabetes mellitus is a global public health problem accompanied by substantial comorbidities and reduced life expectancy. In this respect, CKD leading to uremia can be seen as a systemic disease with a critical impact on virtually all organ systems. Thus it is of particular importance to identify patients with incipient CKD and ongoing CKD progression, but the individual course of CKD is challenging to predict. Patterns of progression in persons with CKD include linear and nonlinear trajectories of glomerular filtration rate (GFR) loss. Kidney function can also remain stable for years, especially in the elderly. In particular, one-fifth of individuals show a substantial GFR decline in the absence of high albuminuria (nonproteinuric CKD), rendering albuminuria less suitable for predicting the progression in such individuals.

Association of Urinary Dickkopf-3 with Residual Renal Function Decline in Patients Undergoing Peritoneal Dialysis

Background and Objectives: Urinary levels of dickkopf-3 (DKK-3) are associated with poor renal survival in patients with non-dialytic chronic kidney disease. However, it remains unknown whether urinary DKK-3 levels can predict residual renal function (RRF) decline in patients undergoing peritoneal dialysis (PD). Therefore, we investigated the correlation between urinary levels of DKK-3 and the subsequent rate of RRF decline in PD patients. Materials and Methods: This study included 36 PD patients who underwent multiple peritoneal equivalent tests during 2011–2021. The relationship between baseline clinical characteristics and the subsequent annual rate of Kt/V decline was investigated. Results: The annual rate of renal Kt/V decline was 0.29 (range: 0.05–0.48), which correlated with renal Kt/V (r = 0.55, p = 0.0005) and 24 h urinary DKK-3 excretion (r = 0.61, p < 0.0001). Similarly, 24 h urinary DKK-3 excretion (β = 0.44, p = 0.0015) and renal Kt/V (β = 0.38, p = 0.0059) were independently associated with the annual rate of renal Kt/V decline in multivariate analyses. Conclusions: Urinary DKK-3 assessment may help identify PD patients at a high risk of RRF decline.

Urinary Dickkopf-3 (uDKK3): a new biomarker for CKD progression and mortality?

BACKGROUND

Kidney fibrosis has been reported to be a prognostic factor in CKD progression. Previous studies have shown that the assessment of urinary Dickkopf-3 (uDKK3), a stress induced tubular epithelial-derived profibrotic glycoprotein, might be a potential tubulointerstitial fibrosis biomarker and might identify patients at short-term risk of eGFR loss. We aim to evaluate uDKK3 as a potential biomarker for progression of CKD in a cohort with various etiologies of CKD, and subsequently in an overt diabetic nephropathy cohort.

METHODS

We prospectively studied two independent cohorts comprising a total of 351 patients with stage 2-3 CKD. Combined primary outcome consisted of a 50% increase in serum creatinine, ESKD or death. Progreser cohort included patients with heterogeneous etiologies and Pronedi cohort 101 patients with overt diabetic nephropathy. Median time of follow-up was 36 (30-39) and 36 (16-48) months, respectively.

RESULTS

At baseline, median uDKK3 was 2200 (671 - 7617) pg/mg in the Progreser cohort and 3042 (661-9747) pg/mg in the Pronedi cohort. There were any statically significant differences in uDKK3 ratio between both cohorts, nor between CKD etiologies. Baseline uDKK3 was significantly higher in patients who reached primary outcome. In the Cox proportional-hazard model, the highest levels of uDKK3 were found to be an independent factor for renal progression in Progreser cohort (HR 1.91, CI95% 1.04 - 3.52) and in Pronedi cohort (HR 3.03, CI95% 1.03-8.92). uDKK3 gradually increased in the following months, especially in patients with higher proteinuria. Treatment with RAAS-blockers did not modify uDKK3 after 4 nor 12 months of treatment.

CONCLUSIONS

uDKK3 identifies patients at high risk of CKD progression regardless of the cause of kidney injury. uDKK3 might serve as a useful biomarker for kidney disease progression and therefore could be used by clinicians to optimize staging for renal progression and monitor the response to potential treatments.

Dickkopf-related protein 3 is a novel biomarker for chronic GVHD after allogeneic hematopoietic cell transplantation

To identify plasma biomarkers associated with fibrotic mechanisms of chronic graft-versus-host disease (GVHD), we used multiplex mass spectrometry with pooled samples for biomarker discovery in comparing proteomic profiles between patients with newly diagnosed sclerotic chronic GVHD (n = 21), those with newly diagnosed nonsclerotic chronic GVHD (n = 33), and those without chronic GVHD (n = 20). Immunoassay was used to measure protein concentrations of individual discovery samples and 186 independent verification samples. The discovery mass spectrometry analysis identified 2 candidate proteins with at least 1.5-fold difference in sclerotic GVHD: Dickkopf-related protein 3 (DKK3) and interleukin-1 receptor accessory protein (IL1RAP). Analysis of individual discovery samples by immunoassay showed that DKK3, a modulator of the Wnt signaling pathway, was a biomarker for both sclerotic and nonsclerotic chronic GVHD. Verification analysis of 186 patients confirmed that elevated plasma DKK3 concentrations were associated with chronic GVHD, regardless of the presence or absence of sclerosis, and that the area under the receiver operating characteristic curve was 0.85 for association of DKK3 concentrations with chronic GVHD. Multiple linear regression analysis showed that chronic GVHD with or without steroid treatment and patient age were independently associated with DKK3 concentrations. Patients with high DKK3 concentrations had a higher nonrelapse mortality than those with low concentrations. The lower IL1RAP concentrations in patients with sclerotic GVHD compared with other conditions in the discovery cohort were not confirmed in the verification cohort. DKK3 is a novel biomarker for chronic GVHD. Further studies are needed to determine the biological functions of DKK3 in the pathogenesis of chronic GVHD.

The emerging plasma biomarker Dickkopf-3 (DKK3) and its association with renal and cardiovascular disease in the general population

Dickkopf-3 (DKK3) is an emerging biomarker for cardiovascular disease (CVD) and chronic kidney disease (CKD). Herein, baseline DKK3 plasma levels were measured in 8420 subjects from the Prevention of Renal and Vascular ENd-stage Disease (PREVEND) cohort, a large general population cohort, using enzyme-linked immunosorbent assays. Associations with clinical variables and outcomes were analysed. Median DKK3 level was 32.8 ng/ml (28.0–39.0). In multivariable linear regression analysis, the strongest correlates for plasma DKK3 were age, body mass index and estimated glomerular filtration rate (eGFR). At baseline, 564 (6.7%) subjects had CVD (defined as a myocardial infarction and/or cerebrovascular accident) and 1361 (16.2%) subjects had CKD (defined as eGFR < 60 ml/min/1.73m² and/or urinary albumin excretion (UAE) > 30 mg/24 h). Of subjects with known CVD and CKD follow-up status (respectively 7828 and 5548), 669 (8.5%) developed CVD and 951 (17.1%) developed CKD (median follow-up respectively 12.5 and 10.2 years). Crude logistic regression analysis revealed that DKK3 levels were associated with prevalent CVD (Odds ratio: 2.14 [1.76–2.61] per DKK3 doubling, P < 0.001) and CKD (Odds ratio: 1.84 [1.59–2.13] per DKK3 doubling, P < 0.001). In crude Cox proportional hazard regression analysis, higher DKK3 levels were associated with higher risk for new-onset CVD (Hazard ratio: 1.47 [1.13–1.91] per DKK3 doubling, P = 0.004) and CKD (Hazard ratio: 1.45, [1.25–1.69] per DKK3 doubling, P < 0.001). However, these associations remained no longer significant after correction for common clinical variables and risk factors, though independently predicted for new-onset CKD in a subgroup of subjects with the lowest UAE values. Together, DKK3 plasma levels are associated with cardiovascular risk factors, but are generally not independently associated with prevalent and new-onset CVD and CKD and only predicted for new-onset CKD in those subjects with the lowest UAE values.

Ex Vivo Expanded 3D Human Kidney Spheres Engraft Long Term and Repair Chronic Renal Injury in Mice

End-stage renal disease is a worldwide epidemic requiring renal replacement therapy. Harvesting tissue from failing kidneys and autotransplantation of tissue progenitors could theoretically delay the need for dialysis. Here we use healthy and end-stage human adult kidneys to robustly expand proliferative kidney epithelial cells and establish 3D kidney epithelial cultures termed "nephrospheres." Formation of nephrospheres reestablishes renal identity and function in primary cultures. Transplantation into NOD/SCID mice shows that nephrospheres restore self-organogenetic properties lost in monolayer cultures, allowing long-term engraftment as tubular structures, potentially adding nephron segments and demonstrating self-organization as critical to survival. Furthermore, long-term tubular engraftment of nephrospheres is functionally beneficial in murine models of chronic kidney disease. Remarkably, nephrospheres inhibit pro-fibrotic collagen production in cultured fibroblasts via paracrine modulation, while transplanted nephrospheres induce transcriptional signatures of proliferation and release from quiescence, suggesting re-activation of endogenous repair. These data support the use of human nephrospheres for renal cell therapy.

Integrated Proteomic and Phosphoproteomics Analysis of DKK3 Signaling Reveals Activated Kinase in the Most Aggressive Gallbladder Cancer

DKK3 is a secreted protein, which belongs to a family of Wnt antagonists and acts as a potential tumor suppressor in gallbladder cancer. To further understand its tumor suppressor functions, we overexpressed DKK3 in 3 GBC cell lines. We have employed high-resolution mass spectrometry and tandem mass tag (TMT) multiplexing technology along with immobilized metal affinity chromatography to enrich phosphopeptides to check the downstream regulators. In this study, we reported for the first time the alteration in the phosphorylation of 14 kinases upon DKK3 overexpression. In addition, we observed DKK3 induced hyper phosphorylation of 2 phosphatases: PPP1R12A and PTPRA, which have not been reported previously. Canonical pathway analysis of altered molecules indicated differential enrichment of signaling cascades upon DKK3 overexpression in all the 3 cell lines. Protein kinase A signaling, Sirtuin signaling pathway, and Cell Cycle Control of Chromosomal Replication were observed to be differentially activated in the GBC cell lines. Our study revealed, DKK3 overexpression has differential effect based on the aggressive behavior of the cell lines. This study expands the understanding of DKK3-mediated signaling events and can be used as a primary factor for understanding the complex nature of this molecule.

A Review of Specific Biomarkers of Chronic Renal Injury and Their Potential Application in Nonclinical Safety Assessment Studies

A host of novel renal biomarkers have been developed over the past few decades which have enhanced monitoring of renal disease and drug-induced kidney injury in both preclinical studies and in humans. Since chronic kidney disease (CKD) and acute kidney injury (AKI) share similar underlying mechanisms and the tubulointerstitial compartment has a functional role in the progression of CKD, urinary biomarkers of AKI may provide predictive information in chronic renal disease. Numerous studies have explored whether the recent AKI biomarkers could improve upon the standard clinical biomarkers, estimated glomerular filtration rate (eGFR), and urinary albumin to creatinine ratio, for predicting outcomes in CKD patients. This review is an introduction to alternative assays that can be utilized in chronic (>3 months duration) nonclinical safety studies to provide information on renal dysfunction and to demonstrate specific situations where these assays could be utilized in nonclinical drug development. Novel biomarkers such as symmetrical dimethyl arginine, dickkopf homolog 3, and cystatin C predict chronic renal injury in animals, act as surrogates for GFR, and may predict changes in GFR in patients over time, ultimately providing a bridge from preclinical to clinical renal monitoring.

Dickkopf-3: Current Knowledge in Kidney Diseases

Dickkopf-related protein 3 (DKK3) is a secreted glycoprotein that has been implicated in the pathogenesis of a variety of diseases. Recent evidence suggests that urinary DKK3 may serve as a potential biomarker for monitoring kidney disease progression and assessing the effects of interventions. We review the biological role of DKK3 as an agonist in chronic kidney disease (CKD) and autosomal dominant polycystic kidney disease (ADPKD) and as an antagonist in idiopathic membranous nephropathy (IMN). In addition, we present the clinical applications of DKK3 in acute kidney disease and tubulointerstitial fibrosis, suggesting that urine DKK3 may be a potential biomarker for acute kidney disease and CKD. Further research into the mechanism of DKK3 and its use as a diagnostic tool, alone or in combination with other biomarkers, could prove clinically useful for better understanding the pathology of kidney diseases and improving early detection and treatment.

Dickkopf-3 in the prediction of contrast media induced acute kidney injury

Background

Dickkopf-3 (DKK3) has recently been discovered as a urinary biomarker for the prediction of acute kidney injury (AKI) after cardiac surgery. This finding needs to be confirmed for AKI in other clinical settings. The present study investigates whether DKK3 can predict contrast-induced AKI (CI-AKI).

Methods

We performed a prospective study in 490 patients undergoing coronary angiography. Primary endpoint was an increase in serum creatinine concentration ≥ 0.3 mg/dl within 72 h after the procedure. DKK3 was assessed < 24 h before coronary angiography. Predictive accuracy was assessed by receiver operating characteristic (ROC) curves.

Results

CI-AKI was observed in 30 (6.1%) patients, of whom 27 corresponded to stage I and 3 to stage II according to the Acute Kidney Injury Network (AKIN) criteria. Subjects who developed CI-AKI had a 3.8-fold higher urinary DKK3/creatinine ratio than those without CI-AKI (7.5 pg/mg [interquartile range [IQR] 1.2–1392.0] vs. 2.0 pg/mg [IQR 0.9–174.0]; p = 0.047). ROC analysis revealed an area under the curve (AUC) of 0.61. Among subjects without clinically overt chronic kidney disease (estimated glomerular filtration rate [eGFR] > 60 ml/min, urinary albumin creatinine ratio < 30 mg/g), the DKK3/creatinine ratio was 5.4-fold higher in those with subsequent CI-AKI (7.5 pg/mg [IQR 0.9–590.1] vs. 1.38 pg/mg [IQR 0.8–51.0]; p = 0.007; AUC 0.62). Coronary angiography was associated with a 43 times increase in the urinary DKK3/creatinine ratio.

Conclusions

Urinary DKK3 is an independent predictor of CI-AKI even in the absence of overt chronic kidney disease (CKD). The study thereby expands the findings on DKK3 in the prediction of postoperative loss of kidney function to other entities of AKI.

Graphic abstract

A long journey for acute kidney injury biomarkers

Acute kidney injury (AKI) is a life-threatening illness that continues to have an in-hospital mortality rate of patients with AKI ranges from 20% to 50% or greater, depending on underlying conditions. However, it has only marginally declined over the past 25 years. Previous authoritative publications have been pointed out that the lack of useful biomarkers for AKI has limited progress in improving the outcomes of this disorder. The purpose of this paper is to review the recent biomarkers involved in the early detection of AKI and main reasons for the failure to identify new AKI biomarkers. So far, several new AKI biomarkers have been discovered and validated to improve early diagnosis, degree of severity, pathophysiology, differential diagnosis, prediction for major kidney adverse events (MAKE, risk groups for progressive renal failure, need for renal replacement therapy [RRT], or death). These biomarkers can be classified into functional, damage and pre-injury phase biomarkers. However, the clinical use of the studied biomarkers in AKI prediction remains unclear because large prospective multicenter trials have failed to demonstrate troponin-like diagnostic performance. Reasons for the failure to identify AKI biomarkers are the heterogeneity of AKI itself, biomarker limitations and long roads to the validation of candidates for new AKI biomarkers. In an effort to overcome these barriers to identifying new AKI biomarkers, kidney biopsy specimens should be obtained and assessed in human AKI populations. Research in this field should be carried out in a pan-social approach rather than conducted by just a few medical institutions.