Renal AAV2-Mediated Overexpression of Long Non-Coding RNA H19 Attenuates Ischemic Acute Kidney Injury Through Sponging of microRNA-30a-5p

The role of lncRNAs in AKI and CKD: Molecular mechanisms, biomarkers, and potential therapeutic targets

Exosomes, a type of extracellular vesicle, are commonly found in different body fluids and are rich in nucleic acids (circRNA, lncRNAs, miRNAs, mRNAs, tRNAs, etc.), proteins, and lipids. They are involved in intercellular communication. lncRNAs are responsible for the modulation of gene expression, thus affecting the pathological process of kidney injury. This review summarizes the latest knowledge on the roles of exosome lncRNAs and circulating lncRNAs in the pathogenesis, biomarker discovery, and treatment of chronic kidney disease, renal fibrosis, and acute kidney injury, providing an overview of novel regulatory approaches and lncRNA delivery systems.

Long Non-coding RNA MIR22HG Alleviates Ischemic Acute Kidney Injury by Targeting the miR-134-5p/NFAT5 axis

Acute kidney injury (AKI), often triggered by ischemia-reperfusion (I/R) injury, is a critical condition characterized by rapid loss of renal function, leading to high morbidity and mortality. Despite extensive research, therapeutic options for ischemic AKI remain limited, and understanding the molecular mechanisms involved is crucial for developing targeted therapies. Long non-coding RNAs (lncRNAs) have emerged as pivotal regulators of gene expression and cellular processes in various diseases, including cancer and renal injury. This study investigates the role of the lncRNA MIR22HG in mitigating renal injury during ischemic AKI. Using in vivo and in vitro models of I/R-induced AKI in mice and hypoxia/reoxygenation (H/R)-treated renal cells, we demonstrated that MIR22HG expression is significantly downregulated in ischemic AKI conditions. Functional assays showed that overexpression of MIR22HG in these models led to reduced renal cell apoptosis, inflammation, and improved renal function. Mechanistically, MIR22HG exerted its protective effects by negatively regulating miR-134-5p, which in turn alleviated renal injury by upregulating NFAT5, a transcription factor known to mitigate cellular stress. Furthermore, dual-luciferase and RNA pull-down assays confirmed direct interactions between MIR22HG and miR-134-5p, as well as miR-134-5p and NFAT5. Additionally, loss-and-gain-of-function assays demonstrated that overexpression of MIR22HG led to the upregulation of NFAT5, which mitigated renal apoptosis, and inflammation and improved renal function. Collectively, the results of our study highlight the therapeutic potential of targeting the MIR22HG/miR-134-5p/NFAT5 axis in the treatment of ischemic AKI, providing new insights into the molecular regulation of renal cell survival and repair during injury.

Inhibition of LncRNA H19 Attenuates Testicular Torsion-Induced Apoptosis and Preserves Blood-Testis Barrier Integrity

Testicular torsion is a common emergency in adolescents, and can lead to severe ischemia reperfusion injury (IRI). LncRNA H19 has been shown to increase during ischemia, but its role in testicular IRI remains unknown. Focusing on this research gap, we utilized H19 biallelic mutant mice and Sertoli cell line (TM4) to construct in vivo and in vitro models of ischemia/reperfusion (I/R) and oxygen-glucose deprivation/reperfusion (OGD/R). Compared to WT I/R mice, H19-/- I/R mice showed milder tissue disorganization and cell loss, with a more intact blood-testis barrier (BTB). The cell viability decreased, ROS levels and apoptosis-related factors such as Bax/Bcl-2 increased in TM4 cells after OGD/R, whereas these changes were reversed when H19 was knocked down followed by OGD/R (si-H19+OGD/R). In contrast, over-expression of H19 in TM4 cells exacerbates OGD/R-induced cell apoptosis. Through in-depth analysis of KEGG-enriched pathways, the PI3K/AKT pathway was identified as a potential target of H19 modulation. Western blotting confirmed that, in OGD/R cells, elevated H19 levels were accompanied by the excessive AKT phosphorylation and the tight junction marker ZO-1 degradation; and in si-H19+OGD/R cells, the decreased AKT phosphorylation was recovered and the up-regulated ZO-1 expression was weakened simultaneously via using the AKT activator SC79. These results suggest that inhibiting H19 in OGD/R cells might preserve the integrity of the BTB by reversing the excessive phosphorylation of AKT. Moreover, H19 deficiency in si-H19+OGD/R cells alleviated the disturbances in glycolysis, fatty acid biosynthesis, and amino acid metabolism. Our study indicates that H19 might be a potential therapeutic target for clinic testicular I/R treatment.

Adeno-Associated Virus Vectors: Principles, Practices, and Prospects in Gene Therapy

Gene therapy offers promising potential as an efficacious and long-lasting therapeutic option for genetic conditions, by correcting defective mutations using engineered vectors to deliver genetic material to host cells. Among these vectors, adeno-associated viruses (AAVs) stand out for their efficiency, versatility, and safety, making them one of the leading platforms in gene therapy. The enormous potential of AAVs has been demonstrated through their use in over 225 clinical trials and the FDA's approval of six AAV-based gene therapy products, positioning these vectors at the forefront of the field. This review highlights the evolution and current applications of AAVs in gene therapy, focusing on their clinical successes, ongoing developments, and the manufacturing processes required for the rapid commercial growth anticipated in the AAV therapy market. It also discusses the broader implications of these advancements for future therapeutic strategies targeting more complex and multi-systemic conditions and biological processes such as aging. Finally, we explore some of the major challenges currently confronting the field.

Identification of key necroptosis-related genes and immune landscape in patients with immunoglobulin A nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is a major cause of chronic kidney disease (CKD) and kidney failure. Necroptosis is a novel type of programmed cell death that has been proved to be associated with the pathogenesis of infectious disease, cardiovascular disease, neurological disorders and so on. However, the role of necroptosis in IgAN remains unclear.

METHODS

In this study, we explored the role of necroptosis-related genes in the pathogenesis of IgAN using a comprehensive bioinformatics method. Microarray datasets GSE93798 and GSE115857 were downloaded from Gene Expression Omnibus (GEO). "limma" package of R software was employed to identify necroptosis-related differentially expressed genes (NRDEGs) between IgAN and healthy controls. GO and KEGG functional enrichment analysis was performed by Clusterprofiler. Least absolute shrinkage and selection operator (LASSO) regression analysis identified hub NRDEGs. We further established a diagnostic model consisting of 7 diagnostic hub NRDEGs and validated the efficacy by an external dataset. The expression of hub genes was confirmed in sc-RNA dataset GSE171314. Immune infiltration, gene set enrichment analysis and transcription factor binding motifs enrichment analysis were conducted to further uncover their roles.

RESULTS

1076 differentially expressed genes were identified between healthy individuals and IgAN patients from RNA-seq dataset GSE9379. Then we cross-linked them with necroptosis-related genes to obtain 9 NRDEGs. LASSO regression analysis screened out 7 hub genes (JUN, CD274, SERTAD1, NFKBIA, H19, UCHL1 and EZH2) of IgAN. We further conducted functional enrichment analysis and constructed the diagnostic model based on dataset GSE93798. GSE115857 was used as the independent validation cohort and indicated a great predictive efficacy. Immune infiltration, gene set enrichment analysis and transcription factor binding motifs enrichment analysis revealed their potential function. Finally, we screened out four drugs that were predicted to have therapeutic value of IgAN.

CONCLUSIONS

In summary, we identified 7 hub necroptosis-associated genes, which can be used as potential genetic biomarkers for IgAN prediction and treatment. Four drugs were predicted as the potential therapeutic solutions. Collectively, we provided insights into the necroptosis-related mechanisms and treatment of IgAN at the transcriptome level.

Multifunctional layered microneedle patches enable transdermal angiogenesis and immunomodulation for scarless healing of thermal burn injuries

Thermal burn injuries induce substantial alterations in the immune compositions and anatomical structures in the skin, which are characterized by strong inflammatory responses and thick eschar formation on the wound surface. These traits challenge current treatment paradigms due to insufficient drug penetration into affected tissues and the unsatisfactory wound regeneration. Herein, we report a layered microneedle (MN) patch for addressing these challenges in burn injury healing. The MN patch features a core/shell structure with methacrylated gelatin (GelMA) encapsulated with human umbilical vein endothelial cell (HUVECs)-derived hypoxia-induced exosomes (EXO-H) as the bottom layer and sodium alginate (SA) containing naringin (Nar)-loaded CaCO3 nanoparticles (CaCO3@Nar) as the top layer. Upon administration onto thermal burn injury site, the MN patches enable transdermal drug delivery by perforating the eschar. The spontaneous degradation of CaCO3@Nar in the interstitial fluid triggers sustained Nar release to alleviate local inflammation and scavenge excessive reactive oxygen species (ROS). Meanwhile, EXO-H significantly promote the migration and proliferation of HUVECs and enhance their angiogenesis capacity to support scarless wound tissue regeneration. The MN patch in this work successfully promoted scarless healing of skin burn injuries on rat models, providing an approach for thermal burn treatment in the clinics.

Systematic review of microRNAs in human acute kidney injury

INTRODUCTION

Early diagnosis of acute kidney injury (AKI) is limited with current tools. MicroRNAs (miRNAs) are implicated in AKI pathogenesis in preclinical models, but less is known about their role in humans. We conducted a systematic review to identify dysregulated miRNAs in humans with AKI.

METHODS

We searched Ovid MEDLINE, Embase, Web of Science, and CENTRAL (August 21, 2023) for studies of human subjects with AKI. We excluded reviews and pre-clinical studies without human data. The primary outcome was dysregulated miRNAs in AKI. Two reviewers screened abstracts, reviewed full texts, performed data extraction and quality assessment (Newcastle Ottawa Scale).

RESULTS

We screened 2,456 reports and included 92 for synthesis without meta-analysis. All studies except one were observational. Studies were grouped by etiology of AKI: cardiac surgery-associated (CS-AKI, n = 13 studies), sepsis (n = 25), nephrotoxic (n = 9), kidney transplant (n = 26), and other causes (n = 19). In total, 128 miRNAs were identified to be dysregulated across AKI studies (45 miRNAs upregulated, 55 downregulated, 28 both). miR-21 was the most frequently reported (n = 17 studies) and it was increased in all etiologies except CS-AKI where it was decreased (n = 3 studies). Study limitations included bias due to targeted approaches, absence of clinical data/controls, and miRNA normalization methods. Overall study quality was fair (median 5/9, range 2-8 points).

CONCLUSION

Dysregulated miRNAs, particularly miR-21, have potential as AKI biomarkers. These results should be interpreted cautiously due to methodological limitations. Standardized methods and unbiased approaches are needed to validate candidate miRNA biomarkers.Registration: International Prospective Register of Systematic Reviews (PROSPERO CRD42020201253).

Protection of Ndrg2 deficiency on renal ischemia-reperfusion injury via activating PINK1/Parkin-mediated mitophagy

BACKGROUND

Renal ischemia-reperfusion (R-I/R) injury is the most prevalent cause of acute kidney injury, with high mortality and poor prognosis. However, the underlying pathological mechanisms are not yet fully understood. Therefore, this study aimed to investigate the role of N-myc downstream-regulated gene 2 ( Ndrg2 ) in R-I/R injury.

METHODS

We examined the expression of Ndrg2 in the kidney under normal physiological conditions and after R-I/R injury by immunofluorescence staining, real-time polymerase chain reaction, and western blotting. We then detected R-I/R injury in Ndrg2-deficient ( Ndrg2-/- ) mice and wild type ( Ndrg2+/+ ) littermates in vivo , and detected oxygen and glucose deprivation and reperfusion (OGD-R) injury in HK-2 cells. We further conducted transcriptomic sequencing to investigate the role of Ndrg2 in R-I/R injury and detected levels of oxidative stress and mitochondrial damage by dihydroethidium staining, biochemical assays, and western blot. Finally, we measured the levels of mitophagy in Ndrg2+/+ and Ndrg2-/- mice after R-I/R injury or HK-2 cells in OGD-R injury.

RESULTS

Ndrg2 was primarily expressed in renal proximal tubules and its expression was significantly decreased 24 h after R-I/R injury. Ndrg2-/- mice exhibited significantly attenuated R-I/R injury compared to Ndrg2+/+ mice. Transcriptomics profiling showed that Ndrg2 deficiency induced perturbations of multiple signaling pathways, downregulated inflammatory responses and oxidative stress, and increased autophagy following R-I/R injury. Further studies revealed that Ndrg2 deficiency reduced oxidative stress and mitochondrial damage. Notably, Ndrg2 deficiency significantly activated phosphatase and tensin homologue on chromosome ten-induced putative kinase 1 (PINK1)/Parkin-mediated mitophagy. The downregulation of NDRG2 expression significantly increased cell viability after OGD-R injury, increased the expression of heme oxygenase-1, decreased the expression of nicotinamide adenine dinucleotide phosphate oxidase 4, and increased the expression of the PINK1/Parkin pathway.

CONCLUSION

Ndrg2 deficiency might become a therapy target for R-I/R injury by decreasing oxidative stress, maintaining mitochondrial homeostasis, and activating PINK1/Parkin-mediated mitophagy.

Pseudogene GSTM3P1 derived long non-coding RNA promotes ischemic acute kidney injury by target directed microRNA degradation of kidney-protective mir-668

Long non-coding RNAs (lncRNAs) are a group of epigenetic regulators that have been implicated in kidney diseases including acute kidney injury (AKI). However, very little is known about the specific lncRNAs involved in AKI and the mechanisms underlying their pathologic roles. Here, we report a new lncRNA derived from the pseudogene GSTM3P1, which mediates ischemic AKI by interacting with and promoting the degradation of mir-668, a kidney-protective microRNA. GSTM3P1 and its mouse orthologue Gstm2-ps1 were induced by hypoxia in cultured kidney proximal tubular cells. In mouse kidneys, Gstm2-ps1 was significantly upregulated in proximal tubules at an early stage of ischemic AKI. This transient induction of Gstm2-ps1 depends on G3BP1, a key component in stress granules. GSTM3P1 overexpression increased kidney proximal tubular apoptosis after ATP depletion, which was rescued by mir-668. Notably, kidney proximal tubule-specific knockout of Gstm2-ps1 protected mice from ischemic AKI, as evidenced by improved kidney function, diminished tubular damage and apoptosis, and reduced kidney injury biomarker (NGAL) induction. To test the therapeutic potential, Gstm2-ps1 siRNAs were introduced into cultured mouse proximal tubular cells or administered to mice. In cultured cells, Gstm2-ps1 knockdown suppressed ATP depletion-associated apoptosis. In mice, Gstm2-ps1 knockdown ameliorated ischemic AKI. Mechanistically, both GSTM3P1 and Gstm2-ps1 possessed mir-668 binding sites and downregulated the mature form of mir-668. Specifically, GSTM3P1 directly bound to mature mir-668 to induce its decay via target-directed microRNA degradation. Thus, our results identify GSTM3P1 as a novel lncRNA that promotes kidney tubular cell death in AKI by binding mir-668 to inducing its degradation.

LncRNA H19/miR-107 regulates endothelial progenitor cell pyroptosis and promotes flow recovery of lower extremity ischemia through targeting FADD

BACKGROUND

Peripheral artery disease (PAD) is an ischemic disease with a rising incidence worldwide. The lncRNA H19 (H19) is enriched in endothelial progenitor cells (EPCs), and transplantation of pyroptosis-resistant H19-overexpressed EPCs (oe-H19-EPCs) may promote vasculogenesis and blood flow recovery in PAD, especially with critical limb ischemia (CLI).

METHODS

EPCs isolated from human peripheral blood was characterized using immunofluorescence and flow cytometry. Cell proliferation was determined with CCK8 and EdU assays. Cell migration was assessed by Transwell and wound healing assays. The angiogenic potential was evaluated using tube formation assay. The pyroptosis pathway-related protein in EPCs was detected by western blot. The binding sites of H19 and FADD on miR-107 were analyzed using Luciferase assays. In vivo, oe-H19-EPCs were transplanted into a mouse ischemic limb model, and blood flow was detected by laser Doppler imaging. The transcriptional landscape behind the therapeutic effects of oe-H19-EPCs on ischemic limbs were examined with whole transcriptome sequencing.

RESULTS

Overexpression of H19 in EPCs led to an increase in proliferation, migration, and tube formation abilities. These effects were mediated through pyroptosis pathway, which is regulated by the H19/miR-107/FADD axis. Transplantation of oe-H19-EPCs in a mouse ischemic limb model promoted vasculogenesis and blood flow recovery. Whole transcriptome sequencing indicated significant activation of vasculogenesis pathway in the ischemic limbs following treatment with oe-H19-EPCs.

CONCLUSIONS

Overexpression of H19 increases FADD level by competitively binding to miR-107, leading to enhanced proliferation, migration, vasculogenesis, and inhibition of pyroptosis in EPCs. These effects ultimately promote the recovery of blood flow in CLI.

Discovery of mmu-lncRNA129814/hsa-lncRNA582795 as a Potential Biomarker and Intervention Target for Ischemia Reperfusion Injury-Induced AKI

Background

Acute kidney injury (AKI) is associated with higher perioperative mortality and morbidity, as well as increased medical expenses. The molecular mechanisms underlying ischemia-reperfusion (I/R)-induced AKI remain unclear.

Methods and Results

We applied an RT-qPCR assay to measure the expression of mmu-lncRNA129814, hsa-lncRNA582795, and miRNA-494-5p, immunoblotting to detect IL-1α and cleaved caspase-3 expression, and TUNEL staining and flow cytometry (FCM) to evaluate apoptosis. The experiments were conducted using BUMPT and HK-2 cells, as well as C57BL/6J mice. Mechanistically, mmu-lncRNA129814 could sponge miRNA-494-5p and upregulate IL-1α expression to promote cell apoptosis. Furthermore, knockdown of mmu-lncRNA129814 ameliorated I/R-induced progression of AKI by targeting the miRNA-494-5p/IL-1α pathways. Interestingly, hsa-lncRNA582795, a homolog of mmu-lncRNA129814, also promoted I/R-stimulated HK-2 cell apoptosis and AKI progression by regulating the miRNA-494-5p/IL-1α axis. Finally, we found that patients with I/R-induced AKI exhibited significantly elevated plasma and urinary levels of hsa-lncRNA582795 compared to those who underwent ischemia-reperfusion without developing AKI. Spearman's test demonstrated a significant correlation between serum creatinine and plasma hsa-lncRNA582795 in I/R patients. Plasma hsa-lncRNA582795 showed high sensitivity but low specificity (86.7%) compared to urinary hsa-lncRNA582795.

Conclusion

The mmu-lncRNA129814/hsa-lncRNA582795/miRNA-494-5p/IL-1α axis was found to modulate the progression of ischemic AKI, and hsa-lncRNA582795 could act as a diagnosis biomarker and potential therapy target of I/R-induced AKI.

A systematic review of epigenetic interplay in kidney diseases: Crosstalk between long noncoding RNAs and methylation, acetylation of chromatin and histone

The intricate crosstalk between long noncoding RNAs (lncRNAs) and epigenetic modifications such as chromatin/histone methylation and acetylation offer new perspectives on the pathogenesis and treatment of kidney diseases. lncRNAs, a class of transcripts longer than 200 nucleotides with no protein-coding potential, are now recognized as key regulatory molecules influencing gene expression through diverse mechanisms. They modulate the epigenetic modifications by recruiting or blocking enzymes responsible for adding or removing methyl or acetyl groups, such as DNA, N6-methyladenosine (m6A) and histone methylation and acetylation, subsequently altering chromatin structure and accessibility. In kidney diseases such as acute kidney injury (AKI), chronic kidney disease (CKD), diabetic nephropathy (DN), glomerulonephritis (GN), and renal cell carcinoma (RCC), aberrant patterns of DNA/RNA/histone methylation and acetylation have been associated with disease onset and progression, revealing a complex interplay with lncRNA dynamics. Recent studies have highlighted how lncRNAs can impact renal pathology by affecting the expression and function of key genes involved in cell cycle control, fibrosis, and inflammatory responses. This review will separately address the roles of lncRNAs and epigenetic modifications in renal diseases, with a particular emphasis on elucidating the bidirectional regulatory effects and underlying mechanisms of lncRNAs in conjunction with DNA/RNA/histone methylation and acetylation, in addition to the potential exacerbating or renoprotective effects in renal pathologies. Understanding the reciprocal relationships between lncRNAs and epigenetic modifications will not only shed light on the molecular underpinnings of renal pathologies but also present new avenues for therapeutic interventions and biomarker development, advancing precision medicine in nephrology.

Systems Approaches to Cell Culture-Derived Extracellular Vesicles for Acute Kidney Injury Therapy: Prospects and Challenges

Acute kidney injury (AKI) is a heterogeneous syndrome, comprising diverse etiologies of kidney insults that result in high mortality and morbidity if not well managed. Although great efforts have been made to investigate underlying pathogenic mechanisms of AKI, there are limited therapeutic strategies available. Extracellular vesicles (EV) are membrane-bound vesicles secreted by various cell types, which can serve as cell-free therapy through transfer of bioactive molecules. In this review, we first overview the AKI syndrome and EV biology, with a particular focus on the technical aspects and therapeutic application of cell culture-derived EVs. Second, we illustrate how multi-omic approaches to EV miRNA, protein, and genomic cargo analysis can yield new insights into their mechanisms of action and address unresolved questions in the field. We then summarize major experimental evidence regarding the therapeutic potential of EVs in AKI, which we subdivide into stem cell and non-stem cell-derived EVs. Finally, we highlight the challenges and opportunities related to the clinical translation of animal studies into human patients.

Role of epigenetically regulated inflammation in renal diseases

In recent decades, renal disease research has witnessed remarkable advances. Experimental evidence in this field has highlighted the role of inflammation in kidney disease. Epigenetic dynamics and immunometabolic reprogramming underlie the alterations in cellular responses to intrinsic and extrinsic stimuli; these factors determine cell identity and cell fate decisions and represent current research hotspots. This review focuses on recent findings and emerging concepts in epigenetics and inflammatory regulation and their effect on renal diseases. This review aims to summarize the role and mechanisms of different epigenetic modifications in renal inflammation and injury and provide new avenues for future research on inflammation-related renal disease and drug development.

The interplay between H19 and HIF-1α in mitochondrial dysfunction in myocardial infarction

Myocardial infarction(MI) causes prolonged ischemia of infarcted myocardial tissue, which triggers a wide range of hypoxia cellular responses in cardiomyocytes. Emerging evidence has indicated the critical roles of long non-coding RNAs(lncRNAs) in cardiovascular diseases, including MI. The purpose of this study was to investigate the roles of lncRNA H19 and H19/HIF-1α pathway during MI. Results showed that cell injury and mitochondrial dysfunction were induced in hypoxia-treated H9c2 cells, accompanied by an increase in the expression of H19. H19 silencing remarkably diminishes cell injury, inhibits the dysfunctional degree of mitochondria, and decreases the injury of MI rats. Bioinformatics analysis and dual-luciferase assays revealed that H19 was the hypoxia-responsive lncRNA, and HIF-1α induced H19 transcription through direct binding to the H19 promoter. Moreover, H19 participates in the HIF-1α pathway by stabilizing the HIF-1α protein. These results indicated that H19 might be a potential biomarker and therapeutic target for myocardial infarction.

LncRNA-XR_002792574.1-mediated ceRNA network reveals potential biomarkers in myopia-induced retinal ganglion cell damage

BACKGROUND

Long noncoding RNAs (lncRNAs) play a key role in the occurrence and progression of myopia. However, the function of lncRNAs in retinal ganglion cells (RGCs) in the pathogenesis of myopia is still unknown. The aim of our study was to explore the lncRNA-mediated competing endogenous RNA (ceRNA) network in RGCs during the development of myopia.

METHODS

RNA sequencing was performed to analyze lncRNA and mRNA expression profiles in RGCs between guinea pigs with form-deprived myopia (FDM) and normal control guinea pigs, and related ceRNA networks were constructed. Then, potentially important genes in ceRNA networks were verified by qRT‒PCR, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to explore biological functions in the RGCs of FDM guinea pigs. The important genes and related signaling pathways were further verified by qRT‒PCR, immunohistochemistry, immunofluorescence and Western blot in myopia in FDM guinea pigs, FDM mice, and highly myopic adults.

RESULTS

The distribution of RGCs was uneven, the number of RGCs was decreased, and RGC apoptosis was increased in FDM guinea pigs. In total, 873 lncRNAs and 2480 mRNAs were determined to be differentially expressed genes in RGCs from normal control and FDM guinea pigs. Via lncRNA-mediated ceRNA network construction and PCR verification, we found that lncRNA-XR_002792574.1 may be involved in the development of myopia through the miR-760-3p/Adcy1 pathway in RGCs. Further verification in FDM guinea pigs, FDM mice, and highly myopic adults demonstrated that the lncRNA-XR_002792574.1/miR-760-3p/Adcy1 axis in RGCs might be related to cGMP/PKG, the apelin signaling pathway and scleral remodeling.

CONCLUSION

We demonstrated that the lncRNA-XR_002792574.1/miR-760-3p/Adcy1 axis in RGCs might be related to myopia. On the one hand, the lncRNA-XR_002792574.1/miR-760-3p/Adcy1 axis might inhibit the cGMP/PKG and apelin signaling pathways in RGCs, thereby causing RGC damage in myopia. On the other hand, the lncRNA-XR_002792574.1/miR-760-3p/Adcy1 axis may cause myopic scleral remodeling through the ERK-MMP-2 pathway. These findings may reveal novel potential targets in myopia and provide reference value for exploration and development of gene editing therapeutics for hereditary myopia.

LncRNA H19: a novel player in the regulation of diabetic kidney disease

Diabetic kidney disease (DKD), one of the most severe complications of diabetes mellitus (DM), has received considerable attention owing to its increasing prevalence and contribution to chronic kidney disease (CKD) and end-stage kidney disease (ESRD). However, the use of drugs targeting DKD remains limited. Recent data suggest that long non-coding RNAs (lncRNAs) play a vital role in the development of DKD. The lncRNA H19 is the first imprinted gene, which is expressed in the embryo and down-regulated at birth, and its role in tumors has long been a subject of controversy, however, in recent years, it has received increasing attention in kidney disease. The LncRNA H19 is engaged in the pathological progression of DKD, including glomerulosclerosis and tubulointerstitial fibrosis via the induction of inflammatory responses, apoptosis, ferroptosis, pyroptosis, autophagy, and oxidative damage. In this review, we highlight the most recent research on the molecular mechanism and regulatory forms of lncRNA H19 in DKD, including epigenetic, post-transcriptional, and post-translational regulation, providing a new predictive marker and therapeutic target for the management of DKD.

The role of LncRNA-regulated autophagy in AKI

Acute kidney injury (AKI) is a complex clinical syndrome involving a series of pathophysiological processes regulated by multiple pathways at the molecular and cellular level. Long noncoding RNAs (lncRNAs) play an important role in the regulation of epigenetics, and their regulation of autophagy-related genes in AKI has attracted increasing attention. However, the role of lncRNA-regulated autophagy in AKI has not been fully elucidated. Evidence indicated that lncRNAs play regulatory roles in most factors that induce AKI. LncRNAs can regulate autophagy in AKI via a complex network of regulatory pathways to affect the development and prognosis of AKI. This article reviewed and analyzed the pathways of lncRNA regulation of autophagy in AKI in recent years. The results provide new ideas for further study of the pathophysiological process and targeted therapy for AKI.

Ischemic tubular injury: Oxygen-sensitive signals and metabolic reprogramming

The kidneys are the most vulnerable organs to severe ischemic insult that results in cellular hypoxia under pathophysiological conditions. Large amounts of oxygen are consumed by the kidneys, mainly to produce energy for tubular reabsorption. Beyond high oxygen demand and the low oxygen supply, different other factors make kidneys vulnerable to ischemia which is deemed to be a major cause of acute kidney injury (AKI). On the other hand, kidneys are capable of sensing and responding to oxygen alternations to evade harms resulting from inadequate oxygen. The hypoxia-inducible factor (HIF) is the main conserved oxygen-sensing mechanism that maintains homeostasis under hypoxia through direct/indirect regulation of several genes that contribute to metabolic adaptation, angiogenesis, energy conservation, erythropoiesis, and so on. In response to oxygen availability, prolyl-hydroxylases (PHDs) control the HIF stability. This review focuses on the oxygen-sensing mechanisms in kidneys, particularly in proximal tubular cells (PTCs) and discusses the molecules involved in ischemic response and metabolic reprogramming. Moreover, the possible roles of non-coding RNAs (microRNAs and long non-coding RNAs) in the development of ischemic AKI are put forward.

The Mission of Long Non-Coding RNAs in Human Adult Renal Stem/Progenitor Cells and Renal Diseases

Long non-coding RNAs (lncRNAs) are a large, heterogeneous class of transcripts and key regulators of gene expression at both the transcriptional and post-transcriptional levels in different cellular contexts and biological processes. Understanding the potential mechanisms of action of lncRNAs and their role in disease onset and development may open up new possibilities for therapeutic approaches in the future. LncRNAs also play an important role in renal pathogenesis. However, little is known about lncRNAs that are expressed in the healthy kidney and that are involved in renal cell homeostasis and development, and even less is known about lncRNAs involved in human adult renal stem/progenitor cells (ARPC) homeostasis. Here we give a thorough overview of the biogenesis, degradation, and functions of lncRNAs and highlight our current understanding of their functional roles in kidney diseases. We also discuss how lncRNAs regulate stem cell biology, focusing finally on their role in human adult renal stem/progenitor cells, in which the lncRNA HOTAIR prevents them from becoming senescent and supports these cells to secrete high quantities of α-Klotho, an anti-aging protein capable of influencing the surrounding tissues and therefore modulating the renal aging.

Various AAV Serotypes and Their Applications in Gene Therapy: An Overview

Despite scientific discoveries in the field of gene and cell therapy, some diseases still have no effective treatment. Advances in genetic engineering methods have enabled the development of effective gene therapy methods for various diseases based on adeno-associated viruses (AAVs). Today, many AAV-based gene therapy medications are being investigated in preclinical and clinical trials, and new ones are appearing on the market. In this article, we present a review of AAV discovery, properties, different serotypes, and tropism, and a following detailed explanation of their uses in gene therapy for disease of different organs and systems.

Serum Long Noncoding RNA H19 and CKD Progression in IgA Nephropathy

BACKGROUND

IgA nephropathy (IgAN) is one of the most common primary glomerular diseases worldwide, especially in young Asian adults. Long RNA H19 is associated with renal pathologies, such as renal cell injury; however, a connection between serum H19 expression and kidney disease progression has not been demonstrated.

METHOD

Our cohort consisted of 204 patients with IgAN. Serum H19 levels were determined with reverse-transcription quantitative polymerase between 1 May, 2014 and 1 May, 2015. H19 levels were log-transformed and categorical variables were categorized according to cutoff points of a ROC curve. Restricted cubic spline and generalized estimating equation analyses were performed to determine the association between serum H19 and kidney disease progression.

RESULTS

H19 expression was significantly downregulated in patients with IgAN compared to healthy controls. Restricted cubic spline analyses showed that the relationship was negatively and linearly correlated (P for nonlinearly = 0.256). After adjusting for other potential clinical, pathologic, and treatment factors, H19 was found to be a protective factor for prognosis in IgAN (HR, 0.52; 95% CI 0.32-0.84; P = 0.008). ROC curve analysis showed that the clinical value of lncRNA H19 with CKD and area under the ROC curve was 0.746 (95% CI 0.663-0.829; P < 0.001) of the clinical prognostic value of H19. Serum restricted cubic spline analyses showed that the relationship was negatively and linearly correlated (P for non-linearly = 0.256). H19 > 0.097 in patients in IgAN was associated with a reduction of the risk of kidney progression by approximately 70% within 5 years compared to H19≤0.097 (HR, 0.30;95% CI 0.12-0.74; P = 0.009).

CONCLUSION

H19 is an independent protective factor, and a high level of H19 often indicates better renal outcome within 5 years.

Molecular regulation of hypoxia through the lenses of noncoding RNAs and epitranscriptome

Cells maintain homeostasis in response to environmental stress through specific cell stress responses. Hypoxic stress, well known to be associated with diverse solid tumors, is one of the main reasons for cancer-related mortality. Although cells can balance themselves well during hypoxic stress, the underlying molecular mechanisms are not well understood. The enhanced appreciation of diverse roles played by noncoding transcriptome and epigenome in recent years has brought to light the involvement of noncoding RNAs and epigenetic modifiers in hypoxic regulation. The emergence of techniques like deep sequencing has facilitated the identification of large numbers of long noncoding RNAs (lncRNAs) that are differentially regulated in various cancers. Similarly, proteomic studies have identified diverse epigenetic modifiers such as HATs, HDACs, DNMTs, polycomb groups of proteins, and their possible roles in the regulation of hypoxia. The crosstalk between lncRNAs and epigenetic modifiers play a pivotal role in hypoxia-induced cancer initiation and progression. Besides the lncRNAs, several other noncoding RNAs like circular RNAs, miRNAs, and so forth are also expressed during hypoxic conditions. Hypoxia has a profound effect on the expression of noncoding RNAs and epigenetic modifiers. Conversely, noncoding RNAs/epigenetic modifies can regulate the hypoxia signaling axis by modulating the stability of the hypoxia-inducible factors (HIFs). The focus of this review is to illustrate the molecular orchestration underlying hypoxia biology, especially in cancers, which can help in identifying promising therapeutic targets in hypoxia-induced cancers. This article is categorized under: RNA Turnover and Surveillance > Regulation of RNA Stability RNA in Disease and Development > RNA in Disease RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry.

LncRNA H19 promotes tumor angiogenesis in smokers by targeting anti-angiogenic miRNAs

A key concept in drug discovery is the identification of candidate therapeutic targets such as long noncoding RNAs (lncRNAs) because of their extensive involvement in neoplasms, and impressionability by smoking. Induced by exposure to cigarette smoke, lncRNA H19 targets and inactivates miR-29, miR-30a, miR-107, miR-140, miR-148b, miR-199a and miR-200, which control the rate of angiogenesis by inhibiting BiP, DLL4, FGF7, HIF1A, HIF1B, HIF2A, PDGFB, PDGFRA, VEGFA, VEGFB, VEGFC, VEGFR1, VEGFR2 and VEGFR3. Nevertheless, these miRNAs are often dysregulated in bladder cancer, breast cancer, colorectal cancer, glioma, gastric adenocarcinoma, hepatocellular carcinoma, meningioma, non-small-cell lung carcinoma, oral squamous cell carcinoma, ovarian cancer, prostate adenocarcinoma and renal cell carcinoma. As such, the present perspective article seeks to establish an evidence-based hypothetical model of how a smoking-related lncRNA known as H19 might aggravate angiogenesis by interfering with miRNAs that would otherwise regulate angiogenesis in a nonsmoking individual.

Still finding ways to augment the existing management of acute and chronic kidney diseases with targeted gene and cell therapies: Opportunities and hurdles

The rising global incidence of acute and chronic kidney diseases has increased the demand for renal replacement therapy. This issue, compounded with the limited availability of viable kidneys for transplantation, has propelled the search for alternative strategies to address the growing health and economic burdens associated with these conditions. In the search for such alternatives, significant efforts have been devised to augment the current and primarily supportive management of renal injury with novel regenerative strategies. For example, gene- and cell-based approaches that utilize recombinant peptides/proteins, gene, cell, organoid, and RNAi technologies have shown promising outcomes primarily in experimental models. Supporting research has also been conducted to improve our understanding of the critical aspects that facilitate the development of efficient gene- and cell-based techniques that the complex structure of the kidney has traditionally limited. This manuscript is intended to communicate efforts that have driven the development of such therapies by identifying the vectors and delivery routes needed to drive exogenous transgene incorporation that may support the treatment of acute and chronic kidney diseases.

LncRNA 148400 Promotes the Apoptosis of Renal Tubular Epithelial Cells in Ischemic AKI by Targeting the miR-10b-3p/GRK4 Axis

Although recent studies have reported that long non-coding RNA (lncRNA) is involved in the development of ischemic acute kidney injury (AKI), the exact function and regulatory mechanism of lncRNAs in ischemic AKI remain largely unknown. Herein, we found that ischemic injury promoted the expression of lncRNA 148400 in mouse proximal tubule-derived cell line (BUMPT) and C57BL/6J mice. Furthermore, the lncRNA148400 mediates ischemic injury-induced apoptosis of BUMPT cells. Mechanistically, lncRNA 148400 sponged miR-10b-3p to promote apoptosis via GRK4 upregulation. Finally, knockdown of lncRNA 148400 alleviated the I/R-induced deterioration of renal function, renal tubular injury, and cell apoptosis. In addition, cleaved caspase-3 is increased via targeting the miR-10b-3p/GRK4 axis. Collectively, these results showed that lncRNA 148400/miR-10b-3p/GRK4 axis mediated the development of ischemic AKI.

mmu-lncRNA 121686/hsa-lncRNA 520657 induced by METTL3 drive the progression of AKI by targeting miR-328-5p/HtrA3 signaling axis

The pathogenesis of acute kidney injury (AKI) is still not fully understood, and effective interventions are lacking. Here, we explored whether methyltransferase 3 (METTL3) was involved in the progression of AKI via regulation of cell death. We reported that PT（proximal tubule）-METTL3-knockout (KO) noticeably suppressed ischemic-induced AKI via inhibition of renal cell apoptosis. Furthermore, we also found that the expression of mmu-long non-coding RNA (lncRNA) 121686 was upregulated in antimycin-treated Boston University mouse proximal tubule (BUMPT) cells and a mouse ischemia-reperfusion (I/R)-induced AKI model. Functionally, mmu-lncRNA 121686 could promote I/R-induced mouse renal cell apoptosis. Mechanistically, mmu-lncRNA 121686 acted as a competing endogenous RNA (ceRNA) to prevent microRNA miR-328-5p-mediated downregulation of high-temperature requirement factor A 3 (Htra3). PT-mmu-lncRNA 121686-KO mice significantly ameliorated the ischemic-induced AKI via the miR-328-5p/HtrA3 axis. In addition, hsa-lncRNA 520657, homologous with lncRNA 121686, sponged miR-328-5p and upregulated Htra3 to promote I/R-induced human renal cell apoptosis. Interestingly, we found that mmu-lncRNA 121686/hsa-lncRNA 520657 upregulation were dependent on METTL3 via N⁶-methyladenosine (m⁶A) modification. The mmu-lncRNA 121686/miR-328-5p or hsa-lncRNA 520657/miR-328-5p /HtrA3 axis was induced in vitro by METTL3 overexpression; in contrast, this effect was attenuated by METTL3 small interfering RNA (siRNA). Furthermore, we found that PT-METTL3-KO or METTL3 siRNA significantly suppressed ischemic, septic, and vancomycin-induced AKI via downregulation of the mmu-lncRNA 121686/miR-328-5p/HtrA3 axis. Taken together, our data indicate that the METTL3/mmu-lncRNA 121686/hsa-lncRNA 520657/miR-328-5p/HtrA3 axis potentially acts as a therapeutic target for AKI.

KCNQ1OT1 Influences HK-2 Apoptosis and Inflammation in LPS-Induced Acute Renal Injury via Modulating miR-30a-5p/NLRP3 Axis

Objective

To investigate the influence of KCNQ1OT1 on HK-2 apoptosis and inflammation in ARI and its molecular mechanism.

Methods

Normal cultivated HK-2 cells were used as negative control (NC) group. Three different concentrations of lipopolysaccharide (LPS) were used to treat the cells (5 μg/mL, 10 μg/mL, and 20 μg/mL). The groups included si-KCN1OT1+ LPS, si-NC + LPS, miR-30a-5p + LPS, pcDNA-NLRP3+si-KCNQ1OT1 + LPS group, miR-NC + LPS group, and pcDNA + si-KCNQ1OT1 + LPS group. CCK-8 and flow cytometry are used to measure cell viability and apoptosis, while RT-qPCR and Western blotting are used to detect KCNQ1OT1, miR-30a-5p, and NLRP3 mRNA. ELISA was used to detect the levels of TNF-α, IL-6, and IL-1β in HK-2 cells. The targeting relationship among KCNQ1OT1, miR-30a-5p, and NLRP3 was verified.

Results

After the intervention of LPS, the viability of HK-2 cells was decreased, while the apoptosis rates were increased. The mRNA and protein expressions of NLRP3 and KCNQ1OT1 were increased, while the mRNA and protein levels of miR-30a-5p were decreased (P < 0.05). The expressions of Bax and Cleaved-caspase-3 were downregulated after silencing KCNQ1OT1 and overexpressed miR-30a-5p. In addition, the viability of HK-2 cells was improved, and the apoptosis was reduced by inhibiting KCNQ1OT1 and overexpressed miR-30a-5p. Thus, KCNQ1OT1 modulated NLRP3 via targeting miR-30a-5p. Overexpression of NLRP3 reverses KCNQ1OT1 inhibition of LPS-induced apoptosis, activity, and inflammation in HK-2 cells.

Conclusions

Through modulating the miR-30a-5p/NLRP3 axis, inhibition of KCNQ1OT1 may reduce HK-2 apoptosis and inflammation in LPS-induced ARI.

LncRNA ENSMUST00000171502 Induced by HIF-1α Ameliorates Ischemic Acute Kidney Injury via Targeting the miR-130b-3p/Mybl-1 Axis

Background: Numerous studies have suggested that long non-coding RNA (lncRNA) affects the progression of ischemic acute kidney injury (IAKI). However, little information is currently available concerning the mechanisms of lncRNA171502 involved in IAKI. Methods: We applied an RT-qPCR assay for the expression of lncRNA171502 and miRNA-130b-3p, immunoblotting for the detection of Mybl-1-myeloblastosis oncogene-like 1 (Mybl-1) and cleaved caspase-3 (CC3) expression, and flow cytometry (FCM) for the evaluation of apoptosis. Result: Initially, lncRNA171502 was induced by HIF-1α in the mouse proximal tubular (BUMPT) cell line and C57BL/6J mice during ischemic injury. Secondly, ischemic injury-induced BUMPT cell apoptosis was markedly relieved following the overexpression of lncRNA171502. However, this effect was enhanced by the knockdown of lncRNA171502. Mechanistically, lncRNA171502 could sponge miRNA-130b-3p and would subsequently upregulate the expression of Mybl-1 to drive the apoptotic process. Lastly, the overexpression of lncRNA171502 alleviated the development of IAKI by targeting miRNA-130b-3p/Mybl-1 pathways. Conclusions: In summary, the HIF-1α/lncRNA171502/miRNA-130b-3p/Mybl-1 axis prevented the progression of IAKI and might serve as a potential therapeutic target.

Role of Long Noncoding RNAs in the Regulation of Cellular Immune Response and Inflammatory Diseases

Long noncoding RNAs (lncRNAs) are recently discovered genetic regulatory molecules that regulate immune responses and are closely associated with the occurrence and development of various diseases, including inflammation, in humans and animals. Under specific physiological conditions, lncRNA expression varies at the cell or tissue level, and lncRNAs can bind to specific miRNAs, target mRNAs, and target proteins to participate in certain processes, such as cell differentiation and inflammatory responses, via the corresponding signaling pathways. This review article summarizes the regulatory role of lncRNAs in macrophage polarization, dendritic cell differentiation, T cell differentiation, and endothelial and epithelial inflammation. In addition, it describes the molecular mechanism of lncRNAs in acute kidney injury, hepatitis, inflammatory injury of the lung, osteoarthritis, mastitis, and neuroinflammation to provide a reference for the molecular regulatory network as well as the genetic diagnosis and treatment of inflammatory diseases in humans and animals.

Long noncoding RNA SNHG5 promotes podocyte injury via the microRNA-26a-5p/TRPC6 pathway in diabetic nephropathy

Podocyte injury is a characteristic pathological hallmark of diabetic nephropathy (DN). However, the exact mechanism of podocyte injury in DN is incompletely understood. This study was conducted using db/db mice and immortalized mouse podocytes. High-throughput sequencing was used to identify the differentially expressed long noncoding RNAs in kidney of db/db mice. The lentiviral shRNA directed against long noncoding RNA small nucleolar RNA host gene 5 (SNHG5) or microRNA-26a-5p (miR-26a-5p) agomir was used to treat db/db mice to regulate the SNHG5/miR-26a-5p pathway. Here, we found that the expression of transient receptor potential canonical type 6 (TRPC6) was significantly increased in injured podocytes under the condition of DN, which was associated with markedly decreased miR-26a-5p. We determined that miR-26a-5p overexpression ameliorated podocyte injury in DN via binding to 3'-UTR of Trpc6, as evidenced by the markedly reduced activity of luciferase reporters by miR-26a-5p mimic. Then, the upregulated SNHG5 in podocytes and kidney in DN was identified, and it was proved to sponge to miR-26a-5p directly using luciferase activity, RNA immunoprecipitation, and RNA pull-down assay. Knockdown of SNHG5 attenuated podocyte injury in vitro, accompanied by an increased expression of miR-26a-5p and decreased expression of TRPC6, demonstrating that SNHG5 promoted podocyte injury by controlling the miR-26a-5p/TRPC6 pathway. Moreover, knockdown of SNHG5 protects against podocyte injury and progression of DN in vivo. In conclusion, SNHG5 promotes podocyte injury via the miR-26a-5p/TRPC6 pathway in DN. Our findings provide novel insights into the pathophysiology of podocyte injury and a potential new therapeutic strategy for DN.

Neat1 promotes acute kidney injury to chronic kidney disease by facilitating tubular epithelial cells apoptosis via sequestering miR-129-5p

Acute kidney injury (AKI) is increasingly identified as a crucial risk factor for progression to CKD. However, the factors governing AKI to CKD progression remain largely unknown. By high-throughput RNA sequencing, we found that Neat1_2, a transcript variant of Neat1, was upregulated in 40-min ischemia/reperfusion injury (IRI), which resulted in the development of renal fibrotic lesions. The upregulation of Neat1_2 in hypoxia-treated TECs was attributed to p53 transcriptional regulation. Gain- and loss-of-function studies, both in vitro and in vivo, demonstrated that Neat1_2 promoted apoptosis of injured TECs induced by IRI and caused tubulointerstitial inflammation and fibrosis. Mechanistically, Neat1_2 shares miRNA response elements with FADD, CASP-8, and CASP-3. Neat1_2 competitively binds to miR-129-5p and prevents miR-129-5p from decreasing the levels of FADD, CASP-8, and CASP-3, and ultimately facilitates TEC apoptosis. Increased expression of Neat1_2 associated with kidney injury and TEC apoptosis was recapitulated in human AKI, highlighting its clinical relevance. These findings suggest that preventing TEC apoptosis by hindering Neat1_2 expression may be a potential therapeutic strategy for AKI to CKD progression.

Regulation Networks of Non-Coding RNA-Associated ceRNAs in Cisplatin-Induced Acute Kidney Injury

Cisplatin is widely used as a chemotherapeutic drug to treat various solid tumors. However, it often induces severe side effects, including nephrotoxicity, which limits its application in clinical settings. Furthermore, the underlying mechanisms of action are unclear. Here, we applied whole-transcriptome RNA sequencing to a cisplatin-induced acute kidney injury (CP-AKI) mouse model to evaluate competing endogenous RNA (ceRNA) networks. We found 4460 mRNAs, 1851 long non-coding RNAs, 101 circular RNAs, and 102 microRNAs significantly differentially expressed between CP-AKI and control mice. We performed gene set enrichment analysis to reveal the biological functions of the mRNAs and constructed non-coding RNA-associated ceRNA networks in CP-AKI mice. Two ceRNA regulatory pathways, Lhx1os-203/mmu-miR-21a-3p/Slc7a13 and circular RNA_3907/mmu-miR-185-3p/Ptprn, were validated using quantitative real-time PCR. The protein–protein interaction network indicated that Il6, Cxcl1, Cxcl2, and Plk1 serve as hub genes and are highly connected with the inflammatory response or DNA damage. Transcription factors, such as Stat3, Cebpb, and Foxm1, regulate gene expression levels in CP-AKI. Our study provides insight into non-coding RNA-associated ceRNA networks and mRNAs in CP-AKI and identifies potential treatment targets.

Comprehensive analysis of fifteen hub genes to identify a promising diagnostic model, regulated networks, and immune cell infiltration in acute kidney injury

BACKGROUND

Acute kidney injury is a common clinical problem with no sensitive and specific diagnostic biomarkers and definitive treatments. The underlying molecular mechanisms of acute kidney injury are unclear. Therefore, it is pivotal to explore the underlying mechanisms and screen for novel diagnostic biomarkers, and therapeutic targets.

METHODS

The present study identified 15 hub genes by WGCNA analysis. LASSO-based logistic regression analysis was used to select key features and construct a diagnostic model of AKI. In addition, GO and KEGG analyses were performed and TF-mRNA and miRNA-mRNA network analysis and immune infiltration analysis of hub genes were performed to reveal the underlying mechanisms of AKI.

RESULTS

A diagnostic model was constructed by LASSO-based logistic regression analysis and was validated by RT-qPCR based on 15 hub genes. GO and KEGG analyses revealed DEGs were enriched in oxidation-reduction process, cell adhesion, proliferation, migration, and metabolic process. The enriched TFs were BRD2, EP300, ETS1, MYC, SPI1, and ZNF263. The enriched miRNAs were miR-181c-5p, miR-218-5p, miR-485-5p, miR-532-5p and miR-6884-5p. The immune infiltration analysis showed that Macrophages M2 was decreasing significantly revealing a protective factor for further AKI treatment.

CONCLUSIONS

The present study identified 15 hub genes based on WGCNA. Development and validation of a potentially diagnostic model based on 15 hub genes. In addition, exploring the interaction between transcriptional factors and 15 hub genes, and miRNA-mRNA relationship pairs. Furthermore, immune infiltration analysis was performed by analyzing gene expression profiles of AKI. Our study provides some basis for further experimental studies.

MiR-6918-5p prevents renal tubular cell apoptosis by targeting MBD2 in ischemia/reperfusion-induced AKI

AIMS

Although previous studies reported that miRNAs are involved in the progression of acute kidney injury (AKI), their exact function and mechanism in ischemic AKI remains largely unknown. This study aims to define the role of miR-6918-5p in ischemia-reperfusion AKI. Materials and methods The renal arteries of C57BL/6J mice were clamped to establish a model of ischemia-reperfusion renal injury. BUMPT cells were added with Antimycin A and calcium ionophore to establish a model of ATP depletion in vitro. Cell apoptosis was detected by CCK8, flow cytometry and western blot, while HE staining and TUNEL staining were used to assess the degree of kidney damage.

KEY FINDINGS

We suppressed mmu_miR-6918-5p by ischemic injury in vitro and in vivo. We found that ischemia-reperfusion (I/R)-induced renal tubular cell apoptosis and the expression of cleaved caspase3 were enhanced by the inhibitor of mmu_miR-6918-5p; this effect was attenuated by an mmu_miR-6918-5p mimic. Mechanistically, mmu_miR-6918-5p binds to the 3' UTR region of MBD2 and represses its expression. The mmu_miR-6918-5p mimic alleviated the ischemic AKI by targeting MBD2. Conversely, the inhibitor of mmu_miR-6918-5p enhanced the ischemic AKI; this was diminished by MBD2-KO.

SIGNIFICANCE

Mmu_miR-6918-5p protected against the development of ischemic AKI by targeting MBD2.

Icariin and Competing Endogenous RNA Network: A Potential Protective Strategy Against Contrast-Induced Acute Kidney Injury

Background

Icariin presents protective effect in several kidney diseases. However, the role of icariin in contrast-induced acute kidney injury (CIAKI) is still unclear. This study aimed to investigate the effect of icariin in CIAKI, as well as exploring the underlying mechanism from the aspect of interaction between protein-coding genes and non-coding RNAs.

Methods

The effect of icariin was evaluated in both in vivo and in vitro CIAKI models. Rat kidneys were collected for genome-wide sequencing. The differentially expressed genes (DEGs) were screened and visualized by R software. The function annotation of DEGs was analyzed by Metascape. By Cytoscape software, the competing endogenous RNA (ceRNA) network was constructed, and hub genes were selected. Expressions of hub genes were validated by PCR. Association of hub genes in the ceRNA network and renal function was also examined.

Results

Icariin protected against CIAKI in both in vivo and in vitro models. Based on DEGs in icariin pretreated CIAKI rats, lncRNA- and circRNA-associated ceRNA networks were constructed, respectively. Function annotation showed the ceRNA networks were enriched in ERK1 and ERK2 cascade, MAPK signaling and NF-κB signaling. Further, two circRNAs, six lncRNAs, four miRNAs and nine mRNAs were selected as hub genes of the ceRNA network. Among them, eight mRNAs (Acot1, Cbwd1, Ly6i, Map3k14, Mettl2b, Nyap1, Set and Utp20) were negatively correlated with renal function, while one mRNA (Tmem44) was positively correlated with renal function.

Conclusion

Icariin presented a protective effect against CIAKI. The ceRNA network, involving Acot1, Cbwd1, Ly6i, Map3k14, Mettl2, Nyap1, Set, Tmem44 and Utp20, might partially contribute to the underlying mechanism of icariin protection by regulation of ERK1 and ERK2 cascade, MAPK signaling and NF-κB signaling.

LncRNA 122049 suppresses apoptosis of renal tubular epithelial cells in ischemic AKI by targeting the miR-330-5p/ELK1 axis

Several studies have reported that long non-coding RNAs (LncRNAs) were associated with the progression of acute kidney injury (AKI). However, the role and regulation mechanism of lncRNA122049 in ischemic AKI remains unknown. In the present study, we found that lncRNA 122049 protected against the ischemia/reperfusion (I/R) induced apoptosis in BUMPT cells. Mechanistically, the lncRNA 122049 directly sponged miR-330-5p, then increased the expression of ELK1(ETS transcription factor ELK1) to decrease renal cell apoptosis. In addition, miR-330-5p inhibitor completely reversed the pro-apoptotic effect of LncRNA 122049 siRNA on I/R-induced BUMPT cells apoptosis. Finally, overexpression of lncRNA 122049 attenuated ischemic mice AKI via targeting of the miR-330-5p/ELK1 axis. Collectively, the data demonstrated that LncRNA 122049 prevented the I/R-induced renal cell apoptosis via regulation of the miR-330-5p/ELK1 axis, which brings new insights into the pathogenesis and potential targeted treatment of ischemic AKI.

LncRNA ENSMUST_147219 mediates the progression of ischemic acute kidney injury by targeting the miR-221-5p/IRF6 axis

Although previous studies have revealed that long noncoding RNAs (lncRNAs) regulate the progression of ischemic acute kidney injury (AKI), the exact role and mechanism of lncRNA ENSMUST_147219 in ischemic AKI are not clear. In the present study, lncRNA ENSMUST_147219 was induced by ischemic injury in vitro and in vivo. Functionally, lncRNA ENSMUST_147219 mediated apoptosis in mouse proximal tubule‐derived cell line (BUMPT). Mechanistically, lncRNA ENSMUST_147219 sponged the microRNA (miR)-221-5p to upregulate the expression of interferon regulatory factor 6 (IRF6) to drive apoptosis. Finally, knockdown of lncRNA ENSMUST_147219 markedly attenuated the ischemic AKI by targeting the miR-221-5p/IRF6 axis. Collectively, our data demonstrated that lncRNA ENSMUST_147219 promoted the development of ischemic AKI by regulating the miR-221-5p/IRF6 pathway, which could be considered a new therapeutic target for ischemic AKI.

An update on the functional roles of long non‑coding RNAs in ischemic injury (Review)

Ischemic injuries result from ischemia and hypoxia in cells. Tissues and organs receive an insufficient supply of nutrients and accumulate metabolic waste, which leads to the development of inflammation, fibrosis and a series of other issues. Ischemic injuries in the brain, heart, kidneys, lungs and other organs can cause severe adverse effects. Acute renal ischemia induces acute renal failure, heart ischemia induces myocardial infarction and cerebral ischemia induces cerebrovascular accidents, leading to loss of movement, consciousness and possibly, life-threatening disabilities. Existing evidence suggests that long non-coding RNAs (lncRNAs) are regulatory sequences involved in transcription, post-transcription, epigenetic regulation and multiple physiological processes. lncRNAs have been shown to be differentially expressed following ischemic injury, with the severity of the ischemic injury being affected by the upregulation or downregulation of certain types of lncRNA. The present review article provides an extensive summary of the functional roles of lncRNAs in ischemic injury, with a focus on the brain, heart, kidneys and lungs. The present review mainly summarizes the functional roles of lncRNA MALAT1, lncRNA MEG3, lncRNA H19, lncRNA TUG1, lncRNA NEAT1, lncRNA AK139328 and lncRNA CAREL, among which lncRNA MALAT1, in particular, plays a crucial role in ischemic injury and is currently a hot research topic.

An Update of Long-Noncoding RNAs in Acute Kidney Injury

Acute kidney injury (AKI) is a global public health concern with high morbidity, mortality, and medical costs. Despite advances in medicine, effective therapeutic regimens for AKI remain limited. Long non-coding RNAs (lncRNAs) are a subtype of non-coding RNAs, which longer than 200 nucleotides and perform extremely diverse functions in biological processes. Recently, lncRNAs have emerged as promising biomarkers and key mediators to AKI. Meanwhile, existing research reveals that the aberrant expression of lncRNAs has been linked to major pathological processes in AKI, including the inflammatory response, cell proliferation, and apoptosis, via forming the lncRNA/microRNA/target gene regulatory axis. Following a comprehensive and systematic search of the available literature, 87 relevant papers spanning the years 2005 to 2021 were identified. This review aims to provide and update an overview of lncRNAs in AKI, and further shed light on their potential utility as AKI biomarkers and therapeutic targets.

Emerging early diagnostic methods for acute kidney injury

Many factors such as trauma and COVID-19 cause acute kidney injury (AKI). Late AKI have a very high incidence and mortality rate. Early diagnosis of AKI provides a critical therapeutic time window for AKI treatment to prevent progression to chronic renal failure. However, the current clinical detection based on creatinine and urine output isn't effective in diagnosing early AKI. In recent years, the early diagnosis of AKI has made great progress with the advancement of information technology, nanotechnology, and biomedicine. These emerging methods are mainly divided into two aspects: First, predicting AKI through models construct by machine learning; Second, early diagnosis of AKI through detection of newly-discovered early biomarkers. Currently, these methods have shown great potential and become an attractive tool for the early diagnosis of AKI. Therefore, it is very important to discuss and summarize these methods for the early diagnosis of AKI. In this review, we first systematically summarize the application of machine learning in AKI prediction algorithms and specific scenarios. In addition, we introduce the key role of early biomarkers in the progress of AKI, and then comprehensively summarize the application of emerging detection technologies for early AKI. Finally, we discuss current challenges and prospects of machine learning and biomarker detection. The review is expected to provide new insights for early diagnosis of AKI, and provided important inspiration for the design of early diagnosis of other major diseases.

The urinary exosomes derived from premature infants attenuate cisplatin-induced acute kidney injury in mice via microRNA-30a-5p/ mitogen-activated protein kinase 8 (MAPK8)

Acute kidney injury (AKI) is a susceptible factor for chronic kidney disease (CKD). There is still a lack of effective prevention methods in clinical practice. This study investigated the protective effect of the urinary exosomes from premature infants on cisplatin-induced acute kidney injury. Here we isolated exosomes from the fresh urine of premature infants. A C57BL/6 mice model of cisplatin-induced acute kidney injury was given 100 ug urinary exosomes 24 hours after model establishment. The kidneys were collected for pathological examination and the evaluation of renal tubular damage and apoptosis. In the in vitro experiment, human renal cortex/proximal tubular cells (HK-2) were induced by cisplatin to assess the effect of the urine exosomes from premature infants. Exosome microRNA (miRNA) sequencing technology was applied to investigate the miRNAs enriched in exosomes and the dual-luciferase gene reporter system to examine the targeting relationship of the miRNA with target genes. The results indicated that the urinary exosomes could decrease the serum creatinine level and the apoptosis of renal tubular cells, and reduce mice mortality. In addition, miR-30a-5p was the most abundant miRNA in the exosomes. It protected HK-2 cells from cisplatin-induced apoptosis by targeting and down-regulating the mitogen-activated protein kinase 8 (MAPK8). Together, our findings identified that the urinary exosomes derived from premature infants alleviated cisplatin-induced acute kidney injury and inhibited the apoptosis of HK-2 via miR-30a-5p, which could target MAPK8. These findings implied that urinary exosomes from premature infants riched in miR-30a-5p might become a potential treatment for AKI.

Spiny mice activate unique transcriptional programs after severe kidney injury regenerating organ function without fibrosis

Fibrosis-driven solid organ failure is an enormous burden on global health. Spiny mice (Acomys) are terrestrial mammals that can regenerate severe skin wounds without scars to avoid predation. Whether spiny mice also regenerate internal organ injuries is unknown. Here, we show that despite equivalent acute obstructive or ischemic kidney injury, spiny mice fully regenerate nephron structure and organ function without fibrosis, whereas C57Bl/6 or CD1 mice progress to complete organ failure with extensive renal fibrosis. Two mechanisms for vertebrate regeneration have been proposed that emphasize either extrinsic (pro-regenerative macrophages) or intrinsic (surviving cells of the organ itself) controls. Comparative transcriptome analysis revealed that the Acomys genome appears poised at the time of injury to initiate regeneration by surviving kidney cells, whereas macrophage accumulation was not detected until about day 7. Thus, we provide evidence for rapid activation of a gene expression signature for regenerative wound healing in the spiny mouse kidney.

Riclinoctaose Attenuates Renal Ischemia-Reperfusion Injury by the Regulation of Macrophage Polarization

Renal ischemia-reperfusion injury is a major trigger of acute kidney injury and leads to permanent renal impairment, and effective therapies remain unresolved. Riclinoctaose is an immunomodulatory octasaccharide composed of glucose and galactose monomers. Here we investigated whether riclinoctaose protects against renal ischemia-reperfusion injury. In mice, pretreatment with riclinoctaose significantly improved renal function, structure, and the inflammatory response after renal ischemia-reperfusion. Flow cytometry analysis revealed that riclinoctaose inhibited ischemia-reperfusion-induced M1 macrophage polarization and facilitated M2 macrophage recruitment into the kidneys. In isolated mouse bone marrow-derived macrophages, pretreatment with riclinoctaose promoted the macrophage polarization toward M2-like phenotype. The inhibitor of Nrf-2/HO-1 brusatol diminished the effects of riclinoctaose on macrophage polarization. In mice, intravenous injection with riclinoctaose-pretreated bone marrow-derived macrophages also protected against renal ischemia-reperfusion injury. Fluorescence-labeled riclinoctaose specifically bound to the membrane of macrophages. Interfering with mDC-SIGN blocked the riclinoctaose function on M2 polarization of macrophages, consequently impairing the renoprotective effect of riclinoctaose. Our results revealed that riclinoctaose is a potential therapeutic agent in preventing renal ischemia-reperfusion injury.

Non-Coding RNAs in Kidney Diseases: The Long and Short of Them

Recent progress in genomic research has highlighted the genome to be much more transcribed than expected. The formerly so-called junk DNA encodes a miscellaneous group of largely unknown RNA transcripts, which contain the long non-coding RNAs (lncRNAs) family. lncRNAs are instrumental in gene regulation. Moreover, understanding their biological roles in the physiopathology of many diseases, including renal, is a new challenge. lncRNAs regulate the effects of microRNAs (miRNA) on mRNA expression. Understanding the complex crosstalk between lncRNA–miRNA–mRNA is one of the main challenges of modern molecular biology. This review aims to summarize the role of lncRNA on kidney diseases, the molecular mechanisms involved, and their function as emerging prognostic biomarkers for both acute and chronic kidney diseases. Finally, we will also outline new therapeutic opportunities to diminish renal injury by targeting lncRNA with antisense oligonucleotides.