Identification of ferroptosis-related genes and pathways in diabetic kidney disease using bioinformatics analysis

Analysis of m6A-regulated genes and subtype classification in lupus nephritis

BACKGROUND

Lupus nephritis (LN) is the most common and severe clinical manifestation of systemic lupus erythematosus (SLE). N6-methyladenosine (m6A) is a reversible RNA modification and has been implicated in various biological processes. However, the roles of m6A regulators in LN are not fully demonstrated.

METHODS

We downloaded the kidney tissue transcriptome dataset of LN patients and normal controls from the GEO database and extracted the expression levels of m6A regulators. We constructed and compared Random Forest (RF) and Support Vector Machine (SVM) models, and subsequently selected featured genes to develop nomogram models. The m6A subtypes were identified based on significantly differentially expressed m6A regulators, and the m6A gene subtypes were identified based on m6A-associated differential genes, and the two m6A modification patterns were comprehensively evaluated.

RESULTS

We obtained the GSE32591 and GSE112943 datasets from the GEO database, including 78 LN samples and 36 normal control samples. We extracted the expression levels of 20 m6A regulators. By RF analysis we identified 7 characteristic m6A regulators and constructed nomogramh models with these 7 genes. We identified two m6A subtypes based on these seven important m6A regulators, and the immune cell infiltration levels of the two subtype clusters were significantly different. We identified two more m6A gene subtypes based on m6A-associated DEGs. We calculated the m6A scores using the principal component analysis (PCA) algorithm and found that the m6A scores of m6A cluster A and gene cluster A were lower than those of m6A cluster B and gene cluster B. In addition, we found that the levels of inflammatory factors were also significantly different between m6A clusters and gene clusters.

CONCLUSION

This study confirms that m6A regulators are involved in the LN process through different modes of action and provide new diagnostic and therapeutic targets for LN.

Identification and Validation of Glomeruli Cellular Senescence-Related Genes in Diabetic Nephropathy by Multiomics

Accumulating evidence indicates that cellular premature senescence of the glomerulus, including endothelial cells, mesangial cells, and podocytes leads to diabetic nephropathy (DN), and DN is regarded as a clinical model of premature senescence. However, the role of cellular senescence-associated genes in the glomerulus in DN progression remains unclear. Therefore, this work aims to identify and validate potential cellular aging-related genes in the glomerulus in DN to provide novel clues for DN treatment based on anti-aging. The microarray GSE96804 dataset, including 41 diabetic glomeruli and 20 control glomeruli, is retrieved from the Gene Expression Omnibus (GEO) database and cellular senescence-related genes (CSRGs) are obtained from the GeneCards database and literature reports. Subsequently, PPI, GO, and KEGG enrichment are analyzed by screening the intersection between differentially expressed genes (DEGs) and CSRGs. scRNA-seq dataset GSE127235 is used to verify core genes expression in glomerulocytes of mice. Finally, db/db mice are utilized to validate the hub gene expression in the glomeruli, and high glucose-induced mesangial cells are used to confirm key gene expression. This study reveals that FOS and ZFP36 may play an anti-aging role in DN to ameliorate cell intracellular premature aging in mesangial cells of glomeruli.

Ferroptosis: an important player in the inflammatory response in diabetic nephropathy

Diabetic nephropathy (DN) is a chronic inflammatory disease that affects millions of diabetic patients worldwide. The key to treating of DN is early diagnosis and prevention. Once the patient enters the clinical proteinuria stage, renal damage is difficult to reverse. Therefore, developing early treatment methods is critical. DN pathogenesis results from various factors, among which the immune response and inflammation play major roles. Ferroptosis is a newly discovered type of programmed cell death characterized by iron-dependent lipid peroxidation and excessive ROS production. Recent studies have demonstrated that inflammation activation is closely related to the occurrence and development of ferroptosis. Moreover, hyperglycemia induces iron overload, lipid peroxidation, oxidative stress, inflammation, and renal fibrosis, all of which are related to DN pathogenesis, indicating that ferroptosis plays a key role in the development of DN. Therefore, this review focuses on the regulatory mechanisms of ferroptosis, and the mutual regulatory processes involved in the occurrence and development of DN and inflammation. By discussing and analyzing the relationship between ferroptosis and inflammation in the occurrence and development of DN, we can deepen our understanding of DN pathogenesis and develop new therapeutics targeting ferroptosis or inflammation-related regulatory mechanisms for patients with DN.

Identifying key genes related to the peritubular capillary rarefaction in renal interstitial fibrosis by bioinformatics

Renal interstitial fibrosis (RIF) is a key feature of progressive chronic kidney disease (CKD), characterized by tubular epithelial cell (TEC) hypoxia and peritubular capillary (PTC) rarefaction. However, the mechanisms underlying these processes remain poorly understood. To address this knowledge gap, we conducted a comparative transcriptome analysis of hypoxic and normoxic HK-2 cells, identifying 572 differentially expressed genes (DEGs). Subsequent Gene Ontology (GO), protein‒protein interaction (PPI) network, and hub gene analyses revealed significant enrichment of DEGs in the HIF-1 signaling pathway based on KEGG enrichment analysis. To further explore TEC modulation under hypoxic conditions, we performed chromatin immunoprecipitation (ChIP) sequencing targeting HIF-1α, identifying 2915 genes potentially regulated by HIF-1α. By comparing RNA sequencing and ChIP sequencing data, we identified 43 overlapping DEGs. By performing GO analysis and peak annotation with IGV, we identified two candidate molecules, VEGFA and BTG1, that are associated with angiogenesis and whose gene sequences were reliably bound by HIF-1α. Our study elucidates the molecular mechanisms underlying RIF, providing valuable insights for potential therapeutic interventions.

Ferroptosis: new insight into the mechanisms of diabetic nephropathy and retinopathy

Diabetic nephropathy (DN) and diabetic retinopathy (DR) are the most serious and common diabetes-associated complications. DN and DR are all highly prevalent and dangerous global diseases, but the underlying mechanism remains to be elucidated. Ferroptosis, a relatively recently described type of cell death, has been confirmed to be involved in the occurrence and development of various diabetic complications. The disturbance of cellular iron metabolism directly triggers ferroptosis, and abnormal iron metabolism is closely related to diabetes. However, the molecular mechanism underlying the role of ferroptosis in DN and DR is still unclear, and needs further study. In this review article, we summarize and evaluate the mechanism of ferroptosis and its role and progress in DN and DR, it provides new ideas for the diagnosis and treatment of DN and DR.

Single-cell transcriptomic profiles in the pathophysiology within the microenvironment of early diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease, resulting in a huge socio-economic impact. Kidney is a highly complex organ and the pathogenesis underlying kidney organization involves complex cell-to-cell interaction within the heterogeneous kidney milieu. Advanced single-cell RNA sequencing (scRNA-seq) could reveal the complex architecture and interaction with the microenvironment in early DKD. We used scRNA-seq to investigate early changes in the kidney of db/m mice and db/db mice at the 14th week. Uniform Manifold Approximation and Projection were applied to classify cells into different clusters at a proper resolution. Weighted gene co-expression network analysis was used to identify the key molecules specifically expressed in kidney tubules. Information of cell-cell communication within the kidney was obtained using receptor-ligand pairing resources. In vitro model, human subjects, and co-detection by indexing staining were used to identify the pathophysiologic role of the hub genes in DKD. Among four distinct subsets of the proximal tubule (PT), lower percentages of proliferative PT and PT containing AQP4 expression (PT^AQP4+) in db/db mice induced impaired cell repair activity and dysfunction of renin-angiotensin system modulation in early DKD. We found that ferroptosis was involved in DKD progression, and ceruloplasmin acted as a central regulator of the induction of ferroptosis in PT^AQP4+. In addition, lower percentages of thick ascending limbs and collecting ducts with impaired metabolism function were also critical pathogenic features in the kidney of db/db mice. Secreted phosphoprotein 1 (SPP1) mediated pathogenic cross-talk in the tubular microenvironment, as validated by a correlation between urinary SPP1/Cr level and tubular injury. Finally, mesangial cell-derived semaphorin 3C (SEMA3C) further promoted endothelium-mesenchymal transition in glomerular endothelial cells through NRP1 and NRP2, and urinary SEMA3C/Cr level was positively correlated with glomerular injury. These data identified the hub genes involved in pathophysiologic changes within the microenvironment of early DKD.