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.

Functional gastrointestinal disorders, mental health, genetic susceptibility, and incident chronic kidney disease

BACKGROUND

Whether functional gastrointestinal disorders (FGIDs) are associated with the long-term risk of chronic kidney disease (CKD) remains unclear. We aimed to investigate the prospective association of FGIDs with CKD and examine whether mental health mediated the association.

METHODS

About 416,258 participants without a prior CKD diagnosis enrolled in the UK Biobank between 2006 and 2010 were included. Participants with FGIDs (including irritable bowel syndrome [IBS], dyspepsia, and other functional intestinal disorders [FIDs; mainly composed of constipation]) were the exposure group, and non-FGID participants were the non-exposure group. The primary outcome was incident CKD, ascertained from hospital admission and death registry records. A Cox proportional hazard regression model was used to investigate the association between FGIDs and CKD, and the mediation analysis was performed to investigate the mediation proportions of mental health.

RESULTS

At baseline, 33,156 (8.0%) participants were diagnosed with FGIDs, including 21,060 (5.1%), 8262 (2.0%), and 6437 (1.6%) cases of IBS, dyspepsia, and other FIDs, respectively. During a mean follow-up period of 12.1 years, 11,001 (2.6%) participants developed CKD. FGIDs were significantly associated with a higher risk of incident CKD compared to the absence of FGIDs (hazard ratio [HR], 1.36; 95% confidence interval [CI], 1.28-1.44). Similar results were observed for IBS (HR, 1.27; 95% CI, 1.17-1.38), dyspepsia (HR, 1.30; 95% CI, 1.17-1.44), and other FIDs (HR, 1.60; 95% CI, 1.43-1.79). Mediation analyses suggested that the mental health score significantly mediated 9.05% of the association of FGIDs with incident CKD and 5.63-13.97% of the associations of FGID subtypes with CKD. Specifically, the positive associations of FGIDs and FGID subtypes with CKD were more pronounced in participants with a high genetic risk of CKD.

CONCLUSION

Participants with FGIDs had a higher risk of incident CKD, which was partly explained by mental health scores and was more pronounced in those with high genetic susceptibility to CKD.

Immune cell signatures and inflammatory mediators: unraveling their genetic impact on chronic kidney disease through Mendelian randomization

Prior research has established associations between immune cells, inflammatory proteins, and chronic kidney disease (CKD). Our Mendelian randomization study aims to elucidate the genetic causal relationships among these factors and CKD. We applied Mendelian randomization using genetic variants associated with CKD from a large genome-wide association study (GWAS) and inflammatory markers from a comprehensive GWAS summary. The causal links between exposures (immune cell subtypes and inflammatory proteins) and CKD were primarily analyzed using the inverse variance-weighted, supplemented by sensitivity analyses, including MR-Egger, weighted median, weighted mode, and MR-PRESSO. Our analysis identified both absolute and relative counts of CD28 + CD45RA + CD8 + T cell (OR = 1.01; 95% CI = 1.01-1.02; p < 0.001, FDR = 0.018) (OR = 1.01; 95% CI = 1.00-1.01; p < 0.001, FDR = 0.002), CD28 on CD39 + CD8 + T cell(OR = 0.97; 95% CI = 0.96-0.99; p < 0.001, FDR = 0.006), CD16 on CD14-CD16 + monocyte (OR = 1.02; 95% CI = 1.01-1.03; p < 0.001, FDR = 0.004) and cytokines, such as IL-17A(OR = 1.11, 95% CI = 1.06-1.16, p < 0.001, FDR = 0.001), and LIF-R(OR = 1.06, 95% CI = 1.02-1.10, p = 0.005, FDR = 0.043) that are genetically predisposed to influence the risk of CKD. Moreover, the study discovered that CKD itself may causatively lead to alterations in certain proteins, including CST5(OR = 1.16, 95% CI = 1.09-1.24, p < 0.001, FDR = 0.001). No evidence of reverse causality was found for any single biomarker and CKD. This comprehensive MR investigation supports a genetic causal nexus between certain immune cell subtypes, inflammatory proteins, and CKD. These findings enhance the understanding of CKD's immunological underpinnings and open avenues for targeted treatments.

Podocyte-Specific Deletion of MCP-1 Fails to Protect against Angiotensin II- or Adriamycin-Induced Glomerular Disease

Investigating the role of podocytes in proteinuric disease is imperative to address the increasing global burden of chronic kidney disease (CKD). Studies strongly implicate increased levels of monocyte chemoattractant protein-1 (MCP-1/CCL2) in proteinuric CKD. Since podocytes express the receptor for MCP-1 (i.e., CCR2), we hypothesized that podocyte-specific MCP-1 production in response to stimuli could activate its receptor in an autocrine manner, leading to further podocyte injury. To test this hypothesis, we generated podocyte-specific MCP-1 knockout mice (Podo-Mcp-1fl/fl) and exposed them to proteinuric injury induced by either angiotensin II (Ang II; 1.5 mg/kg/d, osmotic minipump) or Adriamycin (Adr; 18 mg/kg, intravenous bolus). At baseline, there were no between-group differences in body weight, histology, albuminuria, and podocyte markers. After 28 days, there were no between-group differences in survival, change in body weight, albuminuria, kidney function, glomerular injury, and tubulointerstitial fibrosis. The lack of protection in the knockout mice suggests that podocyte-specific MCP-1 production is not a major contributor to either Ang II- or Adr-induced glomerular disease, implicating that another cell type is the source of pathogenic MCP-1 production in CKD.

Reassuring pregnancy outcomes in women with mild COL4A3-5-related disease (Alport syndrome) and genetic type of disease can aid personalized counseling

Individualized pre-pregnancy counseling and antenatal care for women with chronic kidney disease (CKD) require disease-specific data. Here, we investigated pregnancy outcomes and long-term kidney function in women with COL4A3-5 related disease (Alport Syndrome, (AS)) in a large multicenter cohort. The ALPART-network (mAternaL and fetal PregnAncy outcomes of women with AlpoRT syndrome), an international collaboration of 17 centers, retrospectively investigated COL4A3-5 related disease pregnancies after the 20th week. Outcomes were stratified per inheritance pattern (X-Linked AS (XLAS)), Autosomal Dominant AS (ADAS), or Autosomal Recessive AS (ARAS)). The influence of pregnancy on estimated glomerular filtration rate (eGFR)-slope was assessed in 192 pregnancies encompassing 116 women (121 with XLAS, 47 with ADAS, and 12 with ARAS). Median eGFR pre-pregnancy was over 90ml/min/1.73m2. Neonatal outcomes were favorable: 100% live births, median gestational age 39.0 weeks and mean birth weight 3135 grams. Gestational hypertension occurred during 23% of pregnancies (reference: 'general' CKD G1-G2 pregnancies incidence is 4-20%) and preeclampsia in 20%. The mean eGFR declined after pregnancy but remained within normal range (over 90ml/min/1.73m2). Pregnancy did not significantly affect eGFR-slope (pre-pregnancy β=-1.030, post-pregnancy β=-1.349). ARAS-pregnancies demonstrated less favorable outcomes (early preterm birth incidence 3/11 (27%)). ARAS was a significant independent predictor for lower birth weight and shorter duration of pregnancy, next to the classic predictors (pre-pregnancy kidney function, proteinuria, and chronic hypertension) though missing proteinuria values and the small ARAS-sample hindered analysis. This is the largest study to date on AS and pregnancy with reassuring results for mild AS, though inheritance patterns could be considered in counseling next to classic risk factors. Thus, our findings support personalized reproductive care and highlight the importance of investigating kidney disease-specific pregnancy outcomes.

Circulating miR-423-5p levels are associated with carotid atherosclerosis in patients with chronic kidney disease

BACKGROUND AND AIMS

Carotid atherosclerosis is associated with an elevated risk of stroke in patients with chronic kidney disease. However, the molecular basis for the incidence of carotid atherosclerosis in patients with CKD is poorly understood. Here, we investigated whether circulating miR-423-5p is a crucial link between CKD and carotid atherosclerosis.

METHODS AND RESULTS

We recruited 375 participants for a cross-sectional study to examine the occurrence of carotid plaque and plaque thicknesses. Levels of miR-423-5p were determined by qPCR analysis. We found that non-dialysis CKD patients had higher circulating exosomal and plasma miR-423-5p levels, and dialysis-dependent patients had lower miR-423-5p levels than non-dialysis CKD patients. After excluding for the influence of dialysis patients, linear regression analysis indicated that levels of circulating miR-423-5p are negatively correlated with eGFR (P < 0.001). Higher plasma miR-423-5p levels were associated with the incidence and severity of carotid plaques. In parallel, we constructed a murine model of CKD with a 5/6 nephrectomy protocol and performed RNA sequencing studies of aortic tissues. Consistent with these findings in CKD patients, circulating exosomal miR-423-5p levels in CKD mice were elevated. Furthermore, our RNA-seq studies indicated that the putative target genes of miR-423-5p were related to oxidative stress functions for aorta of CKD mice.

CONCLUSION

Levels of miR-423-5p are associated with the presence and severity of carotid plaque in CKD. Data from our mouse model suggests that miR-423-5p likely influences gene expression programs related to oxidative stress in aorta of CKD mice.

The c-Abl-RACK1-FAK signaling axis promotes renal fibrosis in mice through regulating fibroblast-myofibroblast transition

BACKGROUND

Renal fibrosis is a prevalent manifestation of chronic kidney disease (CKD), and effective treatments for this disease are currently lacking. Myofibroblasts, which originate from interstitial fibroblasts, aggregate in the renal interstitium, leading to significant accumulation of extracellular matrix and impairment of renal function. The nonreceptor tyrosine kinase c-Abl (encoded by the Abl1 gene) has been implicated in the development of renal fibrosis. However, the precise role of c-Abl in this process and its involvement in fibroblast-myofibroblast transition (FMT) remain poorly understood.

METHODS

To investigate the effect of c-Abl in FMT during renal fibrosis, we investigated the expression of c-Abl in fibrotic renal tissues of patients with CKD and mouse models. We studied the phenotypic changes in fibroblast or myofibroblast-specific c-Abl conditional knockout mice. We explored the potential targets of c-Abl in NRK-49F fibroblasts.

RESULTS

In this study, fibrotic mouse and cell models demonstrated that c-Abl deficiency in fibroblasts mitigated fibrosis by suppressing fibroblast activation, fibroblast-myofibroblast transition, and extracellular matrix deposition. Mechanistically, c-Abl maintains the stability of the RACK1 protein, which serves as a scaffold for proteins such as c-Abl and focal adhesion kinase at focal adhesions, driving fibroblast activation and differentiation during renal fibrosis. Moreover, specifically targeting c-Abl deletion in renal myofibroblasts could prove beneficial in established kidney fibrosis by reducing RACK1 expression and diminishing the extent of fibrosis.

CONCLUSIONS

Our findings suggest that c-Abl plays a pathogenic role in interstitial fibrosis through the regulation of RACK1 protein stabilization and myofibroblast differentiation, suggesting a promising strategy for the treatment of CKD.

A clustering approach to improve our understanding of the genetic and phenotypic complexity of chronic kidney disease

Chronic kidney disease (CKD) is a complex disorder that causes a gradual loss of kidney function, affecting approximately 9.1% of the world's population. Here, we use a soft-clustering algorithm to deconstruct its genetic heterogeneity. First, we selected 322 CKD-associated independent genetic variants from published genome-wide association studies (GWAS) and added association results for 229 traits from the GWAS catalog. We then applied nonnegative matrix factorization (NMF) to discover overlapping clusters of related traits and variants. We computed cluster-specific polygenic scores and validated each cluster with a phenome-wide association study (PheWAS) on the BioMe biobank (n = 31,701). NMF identified nine clusters that reflect different aspects of CKD, with the top-weighted traits signifying areas such as kidney function, type 2 diabetes (T2D), and body weight. For most clusters, the top-weighted traits were confirmed in the PheWAS analysis. Results were found to be more significant in the cross-ancestry analysis, although significant ancestry-specific associations were also identified. While all alleles were associated with a decreased kidney function, associations with CKD-related diseases (e.g., T2D) were found only for a smaller subset of variants and differed across genetic ancestry groups. Our findings leverage genetics to gain insights into the underlying biology of CKD and investigate population-specific associations.

Causal relationship between basal metabolic rate and kidney function: a bidirectional two-sample mendelian randomization study

Background

The relationship between basal metabolic rate (BMR) and Chronic kidney disease (CKD) remains unclear and controversial. In this study, we investigated the causal role of BMR in renal injury, and inversely, whether altered renal function causes changes in BMR.

Methods

In this two-sample mendelian randomization (MR) study, Genetic data were accessed from published genome-wide association studies (GWAS) for BMR ((n = 454,874) and indices of renal function, i.e. estimated glomerular filtration rate (eGFR) based on creatinine (n =1, 004, 040), CKD (n=480, 698), and blood urea nitrogen (BUN) (n =852, 678) in European. The inverse variance weighted (IVW) random-effects MR method serves as the main analysis, accompanied by several sensitivity MR analyses. We also performed a reverse MR to explore the causal effects of the above indices of renal function on the BMR.

Results

We found that genetically predicted BMR was negatively related to eGFR, (β= -0.032, P = 4.95*10-12). Similar results were obtained using the MR-Egger (β= -0.040, P = 0.002), weighted median (β= -0.04, P= 5.35×10-11) and weighted mode method (β= -0.05, P=9.92×10-7). Higher BMR had a causal effect on an increased risk of CKD (OR =1.36, 95% CI = 1.11-1.66, P =0.003). In reverse MR, lower eGFR was related to higher BMR (β= -0.64, P = 2.32×10-6, IVW analysis). Bidirectional MR supports no causal association was observed between BMR and BUN. Sensitivity analyses confirmed these findings, indicating the robustness of the results.

Conclusion

Genetically predicted high BMR is associated with impaired kidney function. Conversely, genetically predicted decreased eGFR is associated with higher BMR.

[Research on pediatric hereditary kidney disease: from now to the future]

Hereditary kidney disease is an important cause of chronic kidney disease in children. With the progress of genome sequencing, single-cell technology, and organoid cultures, the research on hereditary kidney disease has entered a new era. How to integrate big data resources, discover new disease-causing genes, and develop effective treatment methods will be the focus of future research. This article discusses the classification, research progress, challenges and prospects of pediatric hereditary kidney disease, so as to provide valuable insights into the research of hereditary kidney disease in children.

[Establishment and application of a database for hereditary kidney disease in Chinese children]

Hereditary kidney diseases are common causes of chronic kidney disease (CKD) in children and adolescents, and also has an important role in the onset and progression of CKD in adulthood. Constructing a data sharing registration system for hereditary kidney disease and forming representative data with Chinese population specificity, is of great significance for achieving phenotype and genotype characterization, improving precision management level and mechanism research. The high heterogeneity of the disease and the scattered distribution of patients have led to a lack of understanding and unified management standards for hereditary kidney disease. Led by pediatric nephrology specialists and geneticists, integrating data sources from various centers can leverage clinical resource advantages. Focusing on different subtype disease cohorts, integrating and analyzing data such as genotype, multi-omics, and clinical outcomes, can achieve breakthroughs in the key points of disease diagnosis and treatment.

Rational Engineering of Escherichia coli Nissle 1917 as Live Biotherapeutic to Degrade Uremic Toxin Precursors

Uremic toxins (UTs) are microbiota-derived metabolites that accelerate the progression of kidney damage in patients with chronic kidney disease (CKD). One of the major UTs involved in CKD progression is p-cresol-sulfate (PCS), derived from dietary l-tyrosine (l-Tyr). Here, we engineered a probiotic strain of Escherichia coli Nissle 1917, to convert l-Tyr to the nontoxic compound p-coumaric acid via tyrosine ammonia lyase (TAL). First, a small metagenomic library was assessed to identify the TAL with the greatest whole-cell activity. Second, accessory genes implicated in the import of l-Tyr and export of PCA were overexpressed to enhance l-Tyr degradation by 106% and 56%, respectively. Last, random mutagenesis coupled to a novel selection and screening strategy was developed that identified a TAL variant with a 25% increase in whole-cell activity. Taken together, the final strain exhibits a 183% improvement over initial whole-cell activity and provides a promising candidate to degrade l-Tyr mediated PCS accumulation.

The secreted micropeptide C4orf48 enhances renal fibrosis via an RNA-binding mechanism

Renal interstitial fibrosis is an important mechanism in the progression of chronic kidney disease (CKD) to end-stage kidney disease. However, we lack specific treatments to slow or halt renal fibrosis. Ribosome profiling identified upregulation of a secreted micropeptide, C4orf48 (Cf48), in mouse diabetic nephropathy. Cf48 RNA and protein levels were upregulated in tubular epithelial cells in human and experimental CKD. Serum Cf48 levels were increased in human CKD and correlated with loss of kidney function, increasing CKD stage, and the degree of active interstitial fibrosis. Cf48 overexpression in mice accelerated renal fibrosis, while Cf48 gene deletion or knockdown by antisense oligonucleotides significantly reduced renal fibrosis in CKD models. In vitro, recombinant Cf48 (rCf48) enhanced TGF-β1-induced fibrotic responses in renal fibroblasts and epithelial cells independently of Smad3 phosphorylation. Cellular uptake of Cf48 and its profibrotic response in fibroblasts operated via the transferrin receptor. RNA immunoprecipitation-sequencing identified Cf48 binding to mRNA of genes involved in the fibrotic response, including Serpine1, Acta2, Ccn2, and Col4a1. rCf48 binds to the 3'UTR of Serpine1 and increases mRNA half-life. We identify the secreted Cf48 micropeptide as a potential enhancer of renal fibrosis that operates as an RNA-binding peptide to promote the production of extracellular matrix.

Association between dyslipidemia and the risk of incident chronic kidney disease affected by genetic susceptibility: Polygenic risk score analysis

BACKGROUND

The effect of dyslipidemia on kidney disease outcomes has been inconclusive, and it requires further clarification. Therefore, we aimed to investigate the effects of genetic factors on the association between dyslipidemia and the risk of chronic kidney disease (CKD) using polygenic risk score (PRS).

METHODS

We analyzed data from 373,523 participants from the UK Biobank aged 40-69 years with no history of CKD. Baseline data included plasma levels of total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride, as well as genome-wide genotype data for PRS. Our primary outcome, incident CKD, was defined as a composite of estimated glomerular filtration rate < 60 ml/min/1.73 m2 and CKD diagnosis according to International Classification of Disease-10 codes. The effects of the association between lipid levels and PRS on incident CKD were assessed using the Cox proportional hazards model. To investigate the effect of this association, we introduced multiplicative interaction terms into a multivariate analysis model and performed subgroup analysis stratified by PRS tertiles.

RESULTS

In total, 4,424 participants developed CKD. In the multivariable analysis, PRS was significantly predictive of the risk of incident CKD as both a continuous variable and a categorized variable. In addition, lower total cholesterol, LDL-C, HDL-C, and higher triglyceride levels were significantly associated with the risk of incident CKD. There were interactions between triglycerides and intermediate and high PRS, and the interactions were inversely associated with the risk of incident CKD.

CONCLUSIONS

This study showed that PRS presented significant predictive power for incident CKD and individuals in the low-PRS group had a higher risk of triglyceride-related incident CKD.

Neuronally differentiated macula densa cells regulate tissue remodeling and regeneration in the kidney

Tissue regeneration is limited in several organs, including the kidney, contributing to the high prevalence of kidney disease globally. However, evolutionary and physiological adaptive responses and the presence of renal progenitor cells suggest an existing remodeling capacity. This study uncovered endogenous tissue remodeling mechanisms in the kidney that were activated by the loss of body fluid and salt and regulated by a unique niche of a minority renal cell type called the macula densa (MD). Here, we identified neuronal differentiation features of MD cells that sense the local and systemic environment and secrete angiogenic, growth, and extracellular matrix remodeling factors, cytokines and chemokines, and control resident progenitor cells. Serial intravital imaging, MD nerve growth factor receptor and Wnt mouse models, and transcriptome analysis revealed cellular and molecular mechanisms of these MD functions. Human and therapeutic translation studies illustrated the clinical potential of MD factors, including CCN1, as a urinary biomarker and therapeutic target in chronic kidney disease. The concept that a neuronally differentiated key sensory and regulatory cell type responding to organ-specific physiological inputs controls local progenitors to remodel or repair tissues may be applicable to other organs and diverse tissue-regenerative therapeutic strategies.

Autosomal dominant chronic tubulointerstitial nephropathy: do not forget amyloidosis

Amyloidosis is a rare cause of inherited kidney disease, with most variants responsible for prominent glomerular involvement. In this issue, Kmochová et al. reported the first description of autosomal dominant medullary amyloidosis due to apolipoprotein A4 variants, resulting in slowly progressive chronic kidney disease with minimal proteinuria. Combining next-generation sequencing with histopathological studies incorporating Congo red staining and mass spectrometry should be considered in the diagnostic workup of hereditary tubulointerstitial disorders not identified after routine genetic testing.

Significance of LncRNAs in AKI-to-CKD transition: A therapeutic and diagnostic viewpoint

Acute kidney injury to chronic kidney disease (AKI-to-CKD) transition is a complex intermingling of characteristics of both AKI and CKD. Pathophysiologically, the transition lasts seven days after the AKI episode and thereafter silently progresses towards CKD. Growing reports confirm that the AKI-to-CKD transition is heavily regulated by epigenetic modifiers. Long non-coding RNAs (lncRNAs) share a diverse role in gene regulation at transcriptional and translational levels and have been reported to be involved in the regulation and progression of AKI-to-CKD transition. Several lncRNAs have been considered potential biomarkers for diagnosing kidney disease, including AKI and CKD. Targeting lncRNAs gives a promising therapeutic strategy against kidney diseases. The primitive role of lncRNA in the progression of the AKI-to-CKD transition is yet to be fully understood. As known, the lncRNAs could be used as a biomarker and a therapeutic target to halt the CKD development and progression after AKI. This review aims to deepen our understanding of the current knowledge regarding the involvement of lncRNAs in the AKI-to-CKD transition. This review primarily discusses the role of lncRNAs and the change in their mechanisms during different stages of kidney disease, such as in AKI, AKI-to-CKD transition, and CKD. Further, we have discussed the potential diagnostic and pharmacological outcomes of targeting lncRNAs to prevent or slow the progression of AKI-to-CKD transition.

Critical Role of histone deacetylase 3 in the regulation of kidney inflammation and fibrosis

Chronic kidney disease (CKD) is characterized by kidney inflammation and fibrosis. However, the precise mechanisms leading to kidney inflammation and fibrosis are poorly understood. Since histone deacetylase is involved in inflammation and fibrosis in other tissues, we examined the role of histone deacetylase 3 (HDAC3) in the regulation of inflammation and kidney fibrosis. HDAC3 is induced in the kidneys of animal models of CKD but mice with conditional HDAC3 deletion exhibit significantly reduced fibrosis in the kidneys compared with control mice. The expression of proinflammatory and profibrotic genes was significantly increased in the fibrotic kidneys of control mice, which was impaired in mice with HDAC3 deletion. Genetic deletion or pharmacological inhibition of HDAC3 reduced the expression of proinflammatory genes in cultured monocytes/macrophages. Mechanistically, HDAC3 deacetylates Lys122 of NF-κB p65 subunit turning on transcription. RGFP966, a selective HDAC3 inhibitor, reduced fibrosis in cells and in animal models by blocking NF-κB p65 binding to κB-containing DNA sequences. Thus, our study identified HDAC3 as a critical regulator of inflammation and fibrosis of the kidney through deacetylation of NF-κB unlocking its transcriptional activity. Hence, targeting HDAC3 could serve as a novel therapeutic strategy for CKD.

AHA Life's Essential 8 and new-onset CKD: a prospective cohort study from the UK Biobank

BACKGROUND

The AHA has recently introduced a novel metric, Life's Essential 8, to assess cardiovascular health (CVH). Nevertheless, the association between varying levels of LE8 and the propensity for CKD is still unclear from a large prospective cohort. Our objective is to meticulously examine the relationship between LE8 and its associated susceptibilities to CKD.

METHODS

A total of 251,825 participants free of CKD from the UK Biobank were included. Cardiovascular health was scored using LE8 and categorized as low, moderate, and high. Cox proportional hazard models were employed to evaluate the associations of LE8 scores with new-onset CKD. The genetic risk score for CKD was calculated by a weighted method.

RESULTS

Over a median follow-up of 12.8 years, we meticulously documented 10,124 incident cases of CKD. Remarkably, an increased LE8 score correlated with a significant reduction of risk in new-onset CKD (high LE8 score vs. low LE8 score: HR = 0.300, 95% CI 0.270-0.330, p < 0.001; median LE8 score vs. low LE8 score: HR = 0.531, 95% CI 0.487-0.580, p < 0.001). This strong LE8-CKD association remained robust in extensive subgroup assessments and sensitivity analysis. Additionally, these noteworthy associations between LE8 scores and CKD remained unaffected by genetic predispositions to CKD.

CONCLUSIONS

An elevated degree of CVH, as delineated by the discerning metric LE8, exhibited a pronounced and statistically significant correlation with a marked reduction in the likelihood of CKD occurrence.

Long non-coding RNAs as emerging regulators of miRNAs and epigenetics in diabetes-related chronic kidney disease

Diabetes is one of the major cause of chronic kidney disease (CKD), including "diabetic nephropathy," and is an increasingly prevalent accelerator of the progression of non-diabetic forms of CKD. The long non-coding RNAs (lncRNAs) have come into the limelight in the past few years as one of the emerging weapons against CKD in diabetes. Available data over the past few years demonstrate the interaction of lncRNAs with miRNAs and epigenetic machinery. Interestingly, the evolving data suggest that lncRNAs play a vital role in diabetes-associated CKD by regulation of epigenetic enzymes such as DNA methyltransferase, histone deacetylases, and histone methyltransferases. LncRNAs are also engaged in the regulation of several miRNAs in diabetic nephropathy. Hence this review will elaborate on the association between lncRNAs and their interaction with epigenetic regulators involved in different aspects and thus the progression of CKD in diabetes.

Autosomal dominant ApoA4 mutations present as tubulointerstitial kidney disease with medullary amyloidosis

Sporadic cases of apolipoprotein A-IV medullary amyloidosis have been reported. Here we describe five families found to have autosomal dominant medullary amyloidosis due to two different pathogenic APOA4 variants. A large family with autosomal dominant chronic kidney disease (CKD) and bland urinary sediment underwent whole genome sequencing with identification of a chr11:116692578 G>C (hg19) variant encoding the missense mutation p.L66V of the ApoA4 protein. We identified two other distantly related families from our registry with the same variant and two other distantly related families with a chr11:116693454 C>T (hg19) variant encoding the missense mutation p.D33N. Both mutations are unique to affected families, evolutionarily conserved and predicted to expand the amyloidogenic hotspot in the ApoA4 structure. Clinically affected individuals suffered from CKD with a bland urinary sediment and a mean age for kidney failure of 64.5 years. Genotyping identified 48 genetically affected individuals; 44 individuals had an estimated glomerular filtration rate (eGFR) under 60 ml/min/1.73 m2, including all 25 individuals with kidney failure. Significantly, 11 of 14 genetically unaffected individuals had an eGFR over 60 ml/min/1.73 m2. Fifteen genetically affected individuals presented with higher plasma ApoA4 concentrations. Kidney pathologic specimens from four individuals revealed amyloid deposits limited to the medulla, with the mutated ApoA4 identified by mass-spectrometry as the predominant amyloid constituent in all three available biopsies. Thus, ApoA4 mutations can cause autosomal dominant medullary amyloidosis, with marked amyloid deposition limited to the kidney medulla and presenting with autosomal dominant CKD with a bland urinary sediment. Diagnosis relies on a careful family history, APOA4 sequencing and pathologic studies.

Mice with renal-specific alterations of stem cell-associated signaling develop symptoms of chronic kidney disease but surprisingly no tumors

Previously, we found that Wnt and Notch signaling govern stem cells of clear cell kidney cancer (ccRCC) in patients. To mimic stem cell responses in the normal kidney in vitro in a marker-unbiased fashion, we have established tubular organoids (tubuloids) from total single adult mouse kidney epithelial cells in Matrigel and serum-free conditions. Deep proteomic and phosphoproteomic analyses revealed that tubuloids resembled renewal of adult kidney tubular epithelia, since tubuloid cells displayed activity of Wnt and Notch signaling, long-term proliferation and expression of markers of proximal and distal nephron lineages. In our wish to model stem cell-derived human ccRCC, we have generated two types of genetic double kidney mutants in mice: Wnt-β-catenin-GOF together with Notch-GOF and Wnt-β-catenin-GOF together with a most common alteration in ccRCC, Vhl-LOF. An inducible Pax8-rtTA-LC1-Cre was used to drive recombination specifically in adult kidney epithelial cells. We confirmed mutagenesis of β-catenin, Notch and Vhl alleles on DNA, protein and mRNA target gene levels. Surprisingly, we observed symptoms of chronic kidney disease (CKD) in mutant mice, but no increased proliferation and tumorigenesis. Thus, the responses of kidney stem cells in the tubuloid and genetic systems produced different phenotypes, i.e. enhanced renewal versus CKD.

Multivariate canonical correlation analysis identifies additional genetic variants for chronic kidney disease

Chronic kidney diseases (CKD) have genetic associations with kidney function. Univariate genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) associated with estimated glomerular filtration rate (eGFR) and blood urea nitrogen (BUN), two complementary kidney function markers. However, it is unknown whether additional SNPs for kidney function can be identified by multivariate statistical analysis. To address this, we applied canonical correlation analysis (CCA), a multivariate method, to two individual-level CKD genotype datasets, and metaCCA to two published GWAS summary statistics datasets. We identified SNPs previously associated with kidney function by published univariate GWASs with high replication rates, validating the metaCCA method. We then extended discovery and identified previously unreported lead SNPs for both kidney function markers, jointly. These showed expression quantitative trait loci (eQTL) colocalisation with genes having significant differential expression between CKD and healthy individuals. Several of these identified lead missense SNPs were predicted to have a functional impact, including in SLC14A2. We also identified previously unreported lead SNPs that showed significant correlation with both kidney function markers, jointly, in the European ancestry CKDGen, National Unified Renal Translational Research Enterprise (NURTuRE)-CKD and Salford Kidney Study (SKS) datasets. Of these, rs3094060 colocalised with FLOT1 gene expression and was significantly more common in CKD cases in both NURTURE-CKD and SKS, than in the general population. Overall, by using multivariate analysis by CCA, we identified additional SNPs and genes for both kidney function and CKD, that can be prioritised for further CKD analyses.

Significance of genetic analysis in adult patients with inherited chronic kidney disease

Genetic focal segmental glomerulosclerosis (FSGS) is an important but underestimated cause of inherited proteinuric chronic kidney disease (CKD) in adults. We discuss a case of familial CKD due to inverted formin 2 (INF2) gene mutation, where three siblings had disparate phenotypic presentations ranging from CKD with subnephrotic proteinuria to nephrotic-range proteinuria with collapsing FSGS on kidney biopsy over a period of 8 years. The youngest sibling was the index case. The family agreed to undergo genetic testing only after two more siblings were diagnosed with kidney disease. This case highlights how clinical heterogeneity, absence of family history in the index case, initial lack of specific biopsy-proven diagnosis and reluctance to undergo genetic testing can delay the diagnosis of genetic kidney disease in adults.