NUAK1 Promotes Diabetic Kidney Disease by Accelerating Renal Tubular Senescence via the ROS/P53 Axis.

Diabetic kidney disease (DKD) is a long-term major microvascular complication of uncontrolled hyperglycemia and one of the leading causes of end-stage renal disease (ESDR). The pathogenesis of DKD has not been fully elucidated, and effective therapy to completely halt DKD progression to ESDR is lacking. This study aimed to identify critical molecular signatures and develop novel therapeutic targets for DKD. This study enrolled 10 datasets consisting of 93 renal samples from the National Center of Biotechnology Information (NCBI) Gene Expression Omnibus (GEO). Networkanalyst, Enrichr, STRING, and Cytoscape were used to conduct the differentially expressed genes (DEGs) analysis, pathway enrichment analysis, protein-protein interaction (PPI) network construction, and hub gene screening. The shared DEGs of type 1 diabetic kidney disease (T1DKD) and type 2 diabetic kidney disease (T2DKD) datasets were performed to identify the shared vital pathways and hub genes. Strepotozocin-induced Type 1 diabetes mellitus (T1DM) rat model was prepared, followed by hematoxylin & eosin (HE) staining, and Oil Red O staining to observe the lipid-related morphological changes. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was conducted to validate the key DEGs of interest from a meta-analysis in the T1DKD rat. Using meta-analysis, 305 shared DEGs were obtained. Among the top 5 shared DEGs, Tmem43, Mpv17l, and Slco1a1, have not been reported relevant to DKD. Ketone body metabolism ranked in the top 1 in the KEGG enrichment analysis. Coasy, Idi1, Fads2, Acsl3, Oxct1, and Bdh1, as the top 10 down-regulated hub genes, were first identified to be involved in DKD. The qRT-PCR verification results of the novel hub genes were mostly consistent with the meta-analysis. The positive Oil Red O staining showed that the steatosis appeared in tubuloepithelial cells at 6 w after DM onset. Taken together, abnormal ketone body metabolism may be the key factor in the progression of DKD. Targeting metabolic abnormalities of ketone bodies may represent a novel therapeutic strategy for DKD. These identified novel molecular signatures in DKD merit further clinical investigation.

Markers of and Risk Factors for the Development and Progression of Diabetic Kidney Disease

From a global perspective, diabetic kidney disease (DKD) is the leading cause of not only chronic kidney disease and end-stage renal disease but also cardiovascular disease (CVD). In the early stages of diabetes, patients have a high risk of developing microvascular complications, loss of kidney function, CVD, infection, and death. Hyperglycemia, free fatty acids, and insulin resistance induce metabolic imbalance and DKD initiation. Inflammation is recognized to play a role in DKD pathogenesis. Our recent study indicated that angiopoietin-like protein 2, which is a circulating proinflammatory protein, might be a strong mediator for the development of DKD and a good predictive biomarker of its progression. The need for effective and safe treatment options for complications such as DKD or CVD becomes ever more urgent. Key Messages: Inflammatory mediators have emerged as potential biomarkers and therapeutic targets for DKD.

Background and Aims Inflammation is a main mechanism for the pathogenesis and progression of diabetic kidney disease (DKD). Interleukin-6 (IL-6) is an important inflammatory mediator and different studies have suggested its involvement in the pathogenesis of DKD. The aim of our study was to evaluate the association between IL-6 levels and progression of DKD in patients with type 2 diabetes. We also tested whether the use of optimal doses of RAS blockade in monotherapy had an influence on the levels of IL-6 in comparison with dual blockade. Method IL-6 levels were measured at baseline and after 4 and 12 months in 70 patients included in the PRONEDI trial (EUDRACT 2004-002470-31), a multicenter, randomized controlled clinical trial. The study included type 2 diabetes patients with a clinical diagnosis of DKD, stage 2 or 3 CKD, and a urinary protein/creatinine ratio (UPCR) >300 mg/g (morning urine spot) on 2 separate opportunities. The primary composite endpoint was a >50% increase in baseline serum creatinine, end stage kidney disease (ESKD) or death. Cox regression model was adjusted for potential confounders or modifiers including eGFR calculated using the CKD-EPI equation and UPCR. Mixed models were adjusted to study longitudinal data. Results The recruitment period was 18 months and the median follow-up was 36 (IQR: 20-48) months, after which 27 patients (38.6%) reached the primary endpoint. At baseline mean IL-6 levels in the whole cohort were 4.58 ± 2.90, at 4 months 4.61 ± 3.10 and at 12 months: 6.14 ± 4.97. Patients were further divided into three groups according to the tertiles of baseline IL-6 levels (tertile 1: 0.65–2.65 pg/mL; tertile 2: 2.66–4.83 pg/mL and tertile 3: 4.84–13.30 pg/mL). There were no differences among the groups in demographic characteristics, cardiovascular risk factors, serum creatinine or proteinuria among the groups. Correlation analyses for IL6 and other inflammatory parameters were carried out for all subjects. The results showed that inflammatory parameters had a significant correlation between them. IL-6 levels correlated with TNFα (r: 0.29; 95% CI: 0.05 - 0.49 p= 0.02), C-reactive protein (r= 0.61; 95%CI: 0.44 - 0.74 p<0.01), and PTH (r: 0.30, 95% CI: 0.03-0.54, p=0.03). However, in the univariate analysis only IL-6 tertiles were associated with the primary outcome (OR: 2.41; 95% CI 1.25-4.64, p=0.008). Patients with the highest IL-6 levels (>4.84 pg/ml) experienced a significantly faster evolution to endpoint (mean survival: 33.2 months, CI 95%: 25.2-41.3) than the other 2 groups. In the multivariate Cox regression analysis, the highest levels of IL-6 (Tertile 3) were significantly associated with the primary outcome (HR:3.86; 95%CI: 1.08-13.86) after being adjusted for baseline serum creatinine and proteinuria. The time-dependent area under the ROC curve at two years of follow-up was 0.88 (95% CI: 0.79 - 0.97). The best cut-off IL-6 level was found at 4.68 pg/ml (sensitivity: 100%, specificity: 78.7%) Generalized linear mixed model analysis showed no effect on subsequent IL-6 levels either with RAS blockade monotherapy or dual blockade. Conclusion In conclusion, our results show that higher levels of IL-6 are independently associated with progression of DKD in patients with type 2 diabetes, and that treatment with RAS blockade does not influence these levels. Serum IL-6 may be used as a noninvasive biomarker of progression to ESKD. Since our results show that higher IL-6 levels are associated with a worse renal prognosis, anti- inflammatory drugs that modulate IL-6 could be promising therapeutic agents to improve outcomes. Further studies focusing on the potential applications of anti-IL6 treatment in DKD are warranted.

Background and Aims The fact that activation of the innate immune system and chronic inflammation are closely involved in the pathogenesis of diabetic Kidney disease (DKD). Recent studies have suggested the inflammatory process plays a crucial role in the progression of DKD. Identifying novel inflammatory molecules closely related to the decline of renal function is of significance in diagnosing and predicting the progression of DKD. The weighted gene co-expression network analysis (WGCNA) algorithm represents a novel systems biology method that provide the approach of association between gene modules and clinical traits to find the genes involvement into the certain phenotypic trait. The goal of this study was to identify hub genes and their roles in DKD from the gene sets associated with the decline of renal function by WGCNA. Method The Gene Expression Omnibus (GEO) database and “Nephroseq” website were searched and transcriptome study from DN biopsies with well-established clinical phenotypic data were selected for analysis. Next, we constructed a weighted gene co-expression network and identified modules negatively correlated with eGFR by WGCNA in the data of glomerular tissue. Functional annotations of the genes in modules negatively correlated with eGFR were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Through protein-protein interaction (PPI) analysis and hub gene screening, the hub genes were obtained. Furthermore, we compared the expression level of hub genes between DKD and normal control and drew ROC curves to determine the diagnosis value to DKD of these genes. Results The microarray-based expression datasets GSE30528 were screened out for analysis, which included glomeruli tissue of 9 cases of DKD and 13 cases of control. This microarray platform represented the transcriptome profile of 12411 well-characterized genes. Using WGCNA, a total of 19 gene modules were identified. Then module eigengene were analyzed for correlation with clinical traits of age, sex, ethnicity and eGFR and the “MEhoneydew1” module showed negative associated with eGFR (r=-0.58). GO functional annotation showed that these 551 genes in the “MEhoneydew1” module mainly enriched in the T cell activation. KEGG annotation showed mainly enriched in chemokine signaling pathway. Except for C3, top 10 hub genes, CCR5, CXCR4, CCR7, CCL5, CXCL8, CCR2, CCR1, CX3CR1, C3AR1 and C3, are all members of chemokines or chemokine receptors. Furthermore, we compared the expression level of these 9 genes between DKD and control, and found that all of these 9 genes increased in the DKD group, and the differences of 6 genes, CCR5, CCR7, CCL5, CCR2, CCR1, C3AR1, were of statistical significance. Linear correlation analysis showed that the expression of these 6 genes was negatively correlated with eGFR, and the ROC curve showed that the area under the curve could reach 0.812∼1.0. Conclusion We identified a panel of 6 hub genes focused on chemokines and chemokine receptors critical for decline of renal function of DKD using WGCNA. These genes may serve as biomarkers for diagnosis/prognosis and as putative novel therapeutic targets for DKD.

Understanding, and Reversing, Metabolic Memory Is Within Reach

Diabetic kidney disease is one of the common complications in diabetic patients and has gradually become an important pathogenic factor in chronic kidney disease. Therefore, studying the mechanisms of its occurrence and development is of great significance for the prevention and treatment of diabetic kidney disease. Some researchers have pointed out that there is a phenomenon of hypoxia in diabetic kidney tissue and believe that hypoxia-inducible factor-1α is closely related to the occurrence and progression of diabetic kidney disease. Additionally, the homeostasis of zinc plays a key role in the body's adaptation to hypoxic environments. However, the specific relationship among these three factors remains unclear. This article provides a detailed review of the multiple roles of hypoxia-inducible factor-1α in the pathogenesis of diabetic kidney disease, including: regulating angiogenesis, increasing the expression of erythropoietin, modulating oxidative stress through the PI3K/AKT and HIF-1α/HO-1 pathways, promoting inflammatory cell infiltration and the release of inflammatory factors to induce inflammatory responses, facilitating epithelial-mesenchymal transition, pathological angiogenesis, and promoting the release of fibrotic factors, ultimately leading to renal fibrosis. Furthermore, HIF-1α also participates in the occurrence and development of diabetic kidney disease through mechanisms such as regulating apoptosis, inducing mitochondrial autophagy, and vascular calcification. At the same time, this article clarifies the regulatory role of the trace element zinc on hypoxia-inducible factor-1α in diabetic kidney disease. This article provides references and insights for further research on the pathogenesis and progression of diabetic kidney disease.

Mechanical forces such as glomerular hyperfiltration are crucial in the pathogenesis and progression of diabetic kidney disease. Piezo2 is a mechanosensitive cation channel and plays a major role in various biological and pathophysiological phenomena. We previously reported Piezo2 expression in mouse and rat kidneys and its alteration by dehydration and hypertension. To elucidate the alteration of Piezo2 expression and its consequences in a mouse model of diabetic kidney disease, we used high salt-fed male KK-Ay mice, an accelerated genetic model of diabetic kidney disease. KK-Ay mice exhibited marked obesity, hyperglycemia, elevated blood pressure, higher creatinine clearance, and overt albuminuria. Histopathological analysis revealed glomerular hypertrophy, mesangial expansion, macrophage infiltration, tubular vacuolization, and interstitial fibrosis. The mRNA and protein expression analyses revealed (1) increased fibronectin protein expression in the glomerular areas, (2) upregulated Piezo2 expression in the glomerular mesangial cells and interstitial region, (3) increased Piezo2 and the fibronectin-coding gene Fn1 mRNA, and (4) a strong correlation of Piezo2 expression with that of Fn1 in the kidneys of diabetic kidney disease mice. Piezo2 upregulation and fibronectin accumulation were alleviated by an angiotensin II receptor blocker. In accordance with these in vivo results, in vitro study demonstrated that Piezo2 overexpression increased fibronectin production in HEK293T cells. In conclusion, we demonstrated that Piezo2 expression was upregulated in glomerular mesangial cells in a mouse model of diabetic kidney disease. Our results suggest that Piezo2 contributes to the progression of diabetic kidney disease by mediating glomerular fibronectin production, leading to glomerulosclerosis. Hyperfiltration is crucial in the pathogenesis of diabetic kidney disease. We showed that Piezo2 expression is upregulated in mesangial cells of diabetic kidney disease mice with glomerular fibronectin accumulation. Piezo2 overexpression increased fibronectin production in HEK293T cells. Piezo2 may contribute to diabetic kidney disease progression by mediating glomerular fibronectin production.

Diabetes is a noncommunicable disease and arguably represents the greatest pandemic in human history. Diabetic kidney disease (DKD) is seen in both type 1 and type 2 diabetes and can be detected in up to 30–50% of diabetic subjects. DKD is a progressive chronic kidney disease (CKD) and is a leading cause of mortality and morbidity in patients with diabetes. Renal fibrosis and inflammation are the major pathological features of DKD. There are a large number of independent and overlapping profibrotic and pro-inflammatory pathways involved in the pathogenesis and progression of DKD. Among these pathways, the transforming growth factor-β (TGF-β) pathway plays a key pathological role by promoting fibrosis. Sirtuin-1 (SIRT1) is a protein deacetylase that has been shown to be renoprotective with an anti-inflammatory effect. It is postulated that a reduction in renal SIRT1 levels could play a key role in the pathogenesis of DKD and that restoration of SIRT1 will attenuate DKD. Cell division autoantigen 1 (CDA1) synergistically enhances the profibrotic effect of TGF-β in DKD by regulating the expression of the TGF-β type I receptor (TβRI). CDA1 has also been found to be an inhibitor of SIRT1 in the DNA damage response. Indeed, targeting CDA1 in experimental DKD not only attenuates diabetes-associated renal fibrosis but also attenuates the expression of key pro-inflammatory genes such as tumor necrosis factor-α (TNF-α) and Monocyte Che moattractant Protein-1 (MCP-1). In conclusion, there is a large body of experimental data to support the view that targeting CDA1 is a superior approach to directly targeting TGF-β in DKD since it is not only safe but also efficacious in retarding both fibrosis and inflammation.

FTO-mediated m6 A modification of SOCS1 mRNA promotes the progression of diabetic kidney disease.

Inflammation is a main mechanism for the pathogenesis and progression of diabetic kidney disease (DKD). Interleukin-6 (IL-6) is an important inflammatory mediator that is suggested to be involved in the pathogenesis of DKD. The aim of our study was to evaluate the association between IL-6 levels and progression of DKD in patients with type 2 diabetes mellitus. Materials an methods: IL-6 levels were measured at baseline and after 4 and 12 months in 70 patients included in a multi-center, randomized controlled clinical trial designed to compare the effect of RAS blockers in monotherapy to dual blockade for slowing the progression of DKD. The primary composite endpoint was > 50% increase in baseline serum creatinine, end-stage kidney disease (ESKD), or death. The median follow-up was 36 months, during which 27 patients (38.6%) reached the primary endpoint. Baseline IL-6 levels correlated with TNF-α, C-reactive protein, and PTH levels. Survival analysis showed that patients with the highest IL-6 levels (> 4.84 pg/mL) reached the primary endpoint faster than the other two groups. Multivariate Cox regression analysis showed that baseline IL-6 levels > 4.84 pg/mL (HR 4.10, 95% CI 1.36 - 12.31) were a risk factor for reaching the primary endpoint adjusted for eGFR and proteinuria. Generalized linear mixed model analysis showed no effect on subsequent IL-6 levels either with RAS blockade monotherapy or dual blockade. These results suggest that treatment with RAS blockade does not influence IL-6 levels. IL-6 is independently associated with an increased risk for progression of DKD.

Diabetic kidney disease (DKD) is a serious disease that presents a major health problem worldwide. There is a desperate need to explore novel biomarkers to further facilitate the early diagnosis and effective treatment in DKD patients so that to prevent them to develop end-stage renal disease (ESRD). However, most of regulation mechanisms at genetic level in DKD still remain unclear. In this work-in-progress paper, we describe our innovative methodologies that integrate biological, statistics, and computational approaches to investigate important roles performed by regulations among microRNAs (miRs), long non-coding RNAs (lncRNAs), and messenger RNAs (mRNAs) in DKD. We conducted a series of experiments and identified a list of miRs and lncRNAs as potential novel biomarkers, along with the set of target genes regulated by discovered miRs. Our initial analysis results are promising in better understanding regulation mechanisms of miRs and lncRNAs on the pathogenesis and progression of DKD.

Diabetic kidney disease (DKD) is becoming the leading cause of chronic kidney disease, especially in the industrialized world. Despite mounting evidence has demonstrated that immunity and inflammation are highly involved in the pathogenesis and progression of DKD, the underlying mechanisms remain incompletely understood. Substantial molecules, signaling pathways, and cell types participate in DKD inflammation, by integrating into a complex regulatory network. Most of the studies have focused on individual components, without presenting their importance in the global or system-based processes, which largely hinders clinical translation. Besides, conventional technologies failed to monitor the different behaviors of resident renal cells and immune cells, making it difficult to understand their contributions to inflammation in DKD. Recently, the advancement of omics technologies including genomics, epigenomics, transcriptomics, proteomics, and metabolomics has revolutionized biomedical research, which allows an unbiased global analysis of changes in DNA, RNA, proteins, and metabolites in disease settings, even at single-cell and spatial resolutions. They help us to identify critical regulators of inflammation processes and provide an overview of cell heterogeneity in DKD. This review aims to summarize the application of multiple omics in the field of DKD and emphasize the latest evidence on the interplay of inflammation and DKD revealed by these technologies, which will provide new insights into the role of inflammation in the pathogenesis of DKD and lead to the development of novel therapeutic approaches and diagnostic biomarkers.

This study investigated the causes of Mitochondrial Dysfunction (MD) in Diabetic Kidney Disease (DKD) progression, and identified genes associated with DKD, especially those with significant genetic causal effects, to provide a theoretical basis for DKD treatment. Using a large database and single-cell RNA sequencing (scRNA-seq) data, 333 MDRDEGs were discovered. MDRDEGs were linked to AGE-RAGE signaling, RNA processing, protein transport, and energy metabolism using functional enrichment analysis. Seven MDRDEGs with significant genetic causal effects in DKD were discovered using SMR and MR analyses: ACTN1, ALG11, CCNB1, HIVEP2, MANBA, TUBA1A, and WFS1. Co-localization and scRNA-seq analyses examined these genes' DKD connections. Due to the high significance of its prediction model and DKD expression, ACTN1 was studied in depth. PheWAS and molecular dynamics analysis assessed ACTN1's safety and efficacy as a therapeutic target, and its connection with other symptoms. ACTN1 protein expression in DKD tissues was confirmed by immunofluorescence. Functional enrichment analysis revealed that MDRDEGs were mostly related to AGE-RAGE signaling, RNA processing, protein transport, and energy metabolism. Seven MDRDEGs caused DKD genetically in SMR and MR investigations. Genetic variations in ACTN1, ALG11, MANBA, and TUBA1A were linked to DKD by co-localization studies. scRNA-seq showed a dramatic increase in ACTN1 expression in DKD. Molecular dynamics analysis demonstrated that Dihydroergocristine can safely bind to ACTN1, while the PheWAS investigation found no significant relationships. DKD tissues exhibited higher ACTN1 protein levels via immunofluorescence. This study identified MDRDEGs linked to inflammation, cytoskeletal stabilization, and glucose metabolism pathways critical in Diabetic Kidney Disease (DKD) pathogenesis, highlighting their clinical potential as therapeutic targets. Notably, ACTN1 emerged as a causally linked gene overexpressed in DKD, with the prediction of dihydroergocristine as a targeting compound, offering novel avenues for clinical intervention. This study suggests that ACTN1 may be a therapeutic target for DKD and sheds light on its molecular pathogenesis, clinical prevention, and treatment.

Background Chronic kidney disease (CKD) is the end stage of progressive renal disorders, and effective disease modifying treatments remain elusive. Diabetic kidney disease (DKD) is its leading cause, yet mechanisms and therapies still hold large knowledge gaps. Studies have demonstrated that tubules and interstitium constitute 90 % of renal parenchyma and drive DKD progression; high-glucose milieu induces renal tubular epithelial cell (RTEC) senescence, a process central to DKD onset and worsening. Methods Using PubMed as the primary data source, this review first screened literature on ‘DKD pathogenesis’, revealing that the pivotal role of ‘complement activation-induced cellular senescence’ remains insufficiently characterized. A second, focused search was then conducted on ‘complement system activation’, from which studies explicitly linking complement activation to cellular senescence were distilled. The final corpus is organized around three core dimensions: latest discoveries, current research status, and mechanism-guided therapeutic strategies. Results Cellular senescence, defined as the irreversible growth arrest of cells in response to damaging stimuli, involves various mechanisms such as DNA methylation, oxidative stress, DNA damage response (DDR), mitochondrial dysfunction, and the continuous production of senescence-associated secretory phenotype (SASP) factors. Complement activation induces cellular senescence through the aforementioned processes, thereby promoting and exacerbating both the onset and progression of DKD. Conclusion In the high-glucose milieu, complement activation drives massive C5a release, which accelerates DKD progression by inducing renal tubular cell senescence. C5a-receptor antagonists have already demonstrated potent renoprotective effects, positioning C5a as a central target for future DKD drug development.