KLF6 Promotes Pyroptosis of Renal Tubular Epithelial Cells in Septic Acute Kidney Injury

Knockdown of KLF6 ameliorates myocardial infarction by regulating autophagy via transcriptional regulation of PTTG1

Krüppel-like factor 6 (KLF6) knockdown provides protection against kidney ischemia/reperfusion injury and ischemic stroke. However, it is unclear whether it plays a role in myocardial infarction (MI). Here, the expression of KLF6 was analyzed using the Gene Expression Omnibus (GEO) database and determined in patients with MI. The impact of KLF6 knockdown was further confirmed in in vivo and in vitro models of MI. The interaction between KLF6 and pituitary tumor-transforming gene 1 (PTTG1) was also evaluated. According to the GEO database, KLF6 expression was found to be upregulated in mouse hearts after MI compared to sham-operated mice. The upregulation of KLF6 in hearts from mice post-MI and in patients with MI was confirmed. KLF6 knockdown was found to alleviate myocardial injury, diminish infarct size, and suppress apoptosis and autophagy in mice with MI. In addition, inactivation of the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling was observed after KLF6 knockdown in mice with MI. In an in vitro model of MI, the knockdown of KLF6 increased cell survival and inhibited autophagy through the AMPK/mTOR pathway. In addition, KLF6 interacted with the promoter of PTTG1 and negatively regulated its expression. Knockdown of PTTG1 abolished the function of KLF6 knockdown in vitro. This study demonstrates the protective effect of KLF6 knockdown against MI, which is attributed to the elevation of PTTG1 expression and inhibition of the AMPK/mTOR pathway. These findings provide a novel insight into MI treatment.NEW & NOTEWORTHY Our study demonstrates for the first time the role of Krüppel-like factor 6 (KLF6)/PTTG1 axis in myocardial infarction (MI). This study demonstrates the protective effect of KLF6 knockdown against MI, which is attributed to the elevation of PTTG1 expression and inhibition of the AMPK/mTOR pathway. These findings provide a novel insight into MI treatment.

Integrated Analysis of Gene Expression and Immune Cell Infiltration Reveals Dysregulated Genes and miRNAs in Acute Kidney Injury

Acute Kidney Injury (AKI) is a multifaceted condition characterised by rapid deterioration of renal function, often precipitated by diverse etiologies. A comprehensive understanding of the molecular underpinnings of AKI is pivotal for identifying potential diagnostic markers and therapeutic targets. This study utilised bioinformatics to elucidate gene expression and immune infiltration in AKI. Publicly available mRNA and miRNA datasets were harnessed to discern differentially expressed genes (DEGs) and miRNAs in AKI. The CIBERSORT algorithm was employed to quantify immune cell infiltration in AKI samples. Functional enrichment analyses were conducted to unravel the implicated biological processes. Furthermore, the expression of identified genes and miRNAs was validated by quantitative real-time PCR in an AKI model. Our study revealed significant dysregulation of three genes (Aspn, Clec2h, Tmigd1) and two miRNAs (mmu-miR-21a-3p, mmu-miR-223-3p) in AKI, each with p < 0.0001. These molecular markers are implicated in immune responses, tissue remodelling, and inflammation. We observed notable disturbances in specific immune cells, including activated and immature dendritic cells, M1 macrophages, and subsets of T cells (Treg, Th1, Th17). These alterations correlated significantly with AKI pathology, with dendritic cells and M1 macrophages showing p < 0.01, and T cell subsets demonstrating p < 0.05. These results highlight the intricate involvement of the immune system in AKI and indicate significant enrichment of pathways related to immune response, inflammation, and tissue remodelling, pointing to their pivotal roles in AKI pathophysiology. Our study underscored the significance of immune cell infiltration and dysregulated gene and miRNA expression in AKI. The identified genes (Clec2h, Aspn, and Tmigd1) and miRNAs (mmu-miR-21a-3p and mmu-miR-223-3p) offer potential diagnostic markers and therapeutic avenues for AKI. Subsequent investigations targeting these genes and miRNAs, along with the elucidated pathways, may augment the clinical management and outcomes for AKI patients.

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).

The Protective Role of Baicalin in the Regulation of NLRP3 Inflammasome in Different Diseases

The NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome consists of pro-caspase-1, NLRP3 and apoptosis-related speckle-like protein (ASC). It can detect multiple microorganisms, endogenous danger signals and environmental stimulus including adenosine triphosphate (ATP), urate, cholesterol crystals, and so on, thereby forming activated NLRP3 inflammasome. During the course of the activation of NLRP3 inflammasome, pro-caspase-1 is transformed into activated caspase-1 that results in the maturation and secretion of interleukin-1beta (IL-1β) and IL-18. The dysfunction of NLRP3 inflammasome participates in multiple diseases such as liver diseases, renal diseases, nervous system diseases and diabetes. Baicalin is the primary bioactive component of Scutellaria baicalensis, which has been used since ancient times. Baicalin has many types of biological functions, such as anti-bacterial, anti-tumor and antioxidant. More and more evidence suggests that baicalin regulation of NLRP3 inflammasome is involved in different diseases. However, the mechanism is still elusive. Here, we reviewed the progress of baicalin regulation of NLRP3 inflammasome in many kinds of diseases to lay a foundation for future researches.

Pyroptosis: The Determinator of Cell Death and Fate in Acute Kidney Injury

Background

Acute kidney injury (AKI) is kidney damage that leads to a rapid decline in function. AKI primarily occurs when the tubular epithelium is damaged, causing swelling, loss of brush margin, and eventual apoptosis. Research has shown that tubular epithelial cell damage in AKI is linked to cell cycle arrest, autophagy, and regulation of cell death.

Summary

Pyroptosis, a type of programmed cell death triggered by inflammation, is believed to play a role in the pathophysiology of AKI. Cumulative evidence has shown that pyroptosis is the main cause of tubular cell death in AKI. Thus, targeted intervention of pyroptosis may be a promising therapeutic approach for AKI. This review delves deep into the cutting-edge research surrounding pyroptosis in the context of AKI, shedding light on its intricate mechanisms and potential implications for clinical practice. Additionally, we explore the exciting realm of potential preclinical treatment options for AKI, aiming to pave the way for future therapeutic advancements.

Key Messages

Pyroptosis, a highly regulated form of cell death, plays a crucial role in determining the fate of cells during the development of AKI. This intricate process involves the activation of inflammasomes, which are multi-protein complexes that initiate pyroptotic cell death. By understanding the mechanisms underlying pyroptosis, researchers aim to gain insights into the pathogenesis of AKI and potentially identify new therapeutic targets for this condition.

The chromatin landscape of healthy and injured cell types in the human kidney

There is a need to define regions of gene activation or repression that control human kidney cells in states of health, injury, and repair to understand the molecular pathogenesis of kidney disease and design therapeutic strategies. Comprehensive integration of gene expression with epigenetic features that define regulatory elements remains a significant challenge. We measure dual single nucleus RNA expression and chromatin accessibility, DNA methylation, and H3K27ac, H3K4me1, H3K4me3, and H3K27me3 histone modifications to decipher the chromatin landscape and gene regulation of the kidney in reference and adaptive injury states. We establish a spatially-anchored epigenomic atlas to define the kidney's active, silent, and regulatory accessible chromatin regions across the genome. Using this atlas, we note distinct control of adaptive injury in different epithelial cell types. A proximal tubule cell transcription factor network of ELF3, KLF6, and KLF10 regulates the transition between health and injury, while in thick ascending limb cells this transition is regulated by NR2F1. Further, combined perturbation of ELF3, KLF6, and KLF10 distinguishes two adaptive proximal tubular cell subtypes, one of which manifested a repair trajectory after knockout. This atlas will serve as a foundation to facilitate targeted cell-specific therapeutics by reprogramming gene regulatory networks.

Expression dynamics of microRNA-223/Ras-associated binding protein 12 axis in Stage III/Grade B periodontal disease: A case-control analysis

Background

The intricate interplay between periodontal polymicrobial flora and an altered immune response is the central cause of periodontal disease. Multiple cell death methods and their interactions, along with the associated signaling pathways, significantly impact the initiation and advancement of periodontitis. Our speculation revolves around the role of the miR-223/Ras-associated binding protein (RAB12) signaling axis in regulating autophagy-induced pyroptosis, contributing to the pathophysiology of periodontitis. Thus, this study aimed to investigate miR-223 and RAB12 expression patterns in Stage III/Grade B periodontal disease.

Materials and Methods

The study included 50 healthy individuals and 50 patients diagnosed with Stage III/Grade B periodontal disease. Clinical parameters were cataloged for each participant. miRNA-223 underwent an in silico analysis to identify its potential target genes. Gingival crevicular fluid (GCF) samples were collected from the subjects for real-time polymerase chain reaction to evaluate the expression of both miR-223 and the RAB12 gene.

Results

The miRTargetLink2.0 analysis highlighted the RAB12 gene as a prime target for miR-223. In periodontal disease patients, miR-223 and RAB12 gene expressions significantly increased (15.21 and 34.70-fold changes, respectively; P < 0.05). Receiver operating characteristic analysis suggested that miR-223 is a potential biomarker for periodontal disease, with 76% diagnostic accuracy and an area under the curve of 0.777 (P < 0.01).

Conclusion

MicroRNA-223 and its target gene RAB12 exhibit high expression levels in GCF samples from individuals with periodontal disease. This suggests modulation of autophagy and the signaling mechanism for pyroptotic cell death in periodontal tissues during pathogenesis. Consequently, the miR-223/RAB12 axis might represent a plausible link for periodontal disease.

Hyperoside mediates protection from diabetes kidney disease by regulating ROS-ERK signaling pathway and pyroptosis

Renal tubular injury is a key factor in the progression of diabetic kidney disease to end-stage renal disease. Hyperoside, a natural flavonol glycoside in various plants, is a potentially effective drug for the clinical treatment of diabetic kidney disease. However, the specific mechanisms remain unknown. Therefore, this study will explore the effect and mechanism of hyperoside on renal tubulointerstitium in diabetic kidney disease. db/db mouse (C57BL/KsJ) is a model of type 2 diabetes resulting from Leptin receptor point mutations, with the appearance of diabetic kidney disease. Therefore, db/db mice were used for in vivo experimental studies. In vitro, human renal tubular epithelial cells were incubated with bovine serum albumin to simulate the injury of renal tubular epithelial cells caused by excessive albumin in primary urine. The experimental results showed that hyperoside could improve kidney function and reduce kidney tissue damage in mice, and could inhibit oxidative stress, extracellularly regulated protein kinases 1/2 signaling activation, and pyroptosis in human renal tubular epithelial cells. Therefore, hyperoside inhibited oxidative stress by regulating the activation of the extracellularly regulated protein kinases 1/2/mitogen-activated protein kinase signaling pathway, thereby alleviating proteinuria-induced pyroptosis in renal tubular epithelial cells. This study provides novel evidence that could facilitate the clinical application of hyperoside in diabetic kidney disease treatment.

Gasdermins in sepsis

Sepsis is a hyper-heterogeneous syndrome in which the systemic inflammatory response persists throughout the course of the disease and the inflammatory and immune responses are dynamically altered at different pathogenic stages. Gasdermins (GSDMs) proteins are pore-forming executors in the membrane, subsequently mediating the release of pro-inflammatory mediators and inflammatory cell death. With the increasing research on GSDMs proteins and sepsis, it is believed that GSDMs protein are one of the most promising therapeutic targets in sepsis in the future. A more comprehensive and in-depth understanding of the functions of GSDMs proteins in sepsis is important to alleviate the multi-organ dysfunction and reduce sepsis-induced mortality. In this review, we focus on the function of GSDMs proteins, the molecular mechanism of GSDMs involved in sepsis, and the regulatory mechanism of GSDMs-mediated signaling pathways, aiming to provide novel ideas and therapeutic strategies for the diagnosis and treatment of sepsis.

Roles of noncoding RNAs in septic acute kidney injury

Septic acute kidney injury (SAKI) is one of the most common and life-threatening complications of sepsis. Patients with SAKI have increased mortality. However, the underlying pathogenesis is unclear, and the treatment targeting SAKI is unsatisfactory. Thus, identifying optimal biomarkers for SAKI diagnosis and treatment is an urgent requisite. Accumulating evidence indicates that noncoding RNAs (ncRNAs) are involved in the occurrence and progression of SAKI. In the present review, we summarized the studies of ncRNAs in SAKI, including microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs). The ncRNAs are divided into protective and damage factors according to their role in SAKI, and their expression patterns, functions, and molecular mechanisms were elaborated. Next, we proposed that ncRNAs have the potential to be diagnostic and prognostic biomarkers for SAKI and as new therapeutic targets. This review aimed to provide a comprehensive overview of ncRNAs in SKAI and explored the clinical value of ncRNAs as ideal biomarkers of SAKI.

The chromatin landscape of healthy and injured cell types in the human kidney

There is a need to define regions of gene activation or repression that control human kidney cells in states of health, injury, and repair to understand the molecular pathogenesis of kidney disease and design therapeutic strategies. However, comprehensive integration of gene expression with epigenetic features that define regulatory elements remains a significant challenge. We measured dual single nucleus RNA expression and chromatin accessibility, DNA methylation, and H3K27ac, H3K4me1, H3K4me3, and H3K27me3 histone modifications to decipher the chromatin landscape and gene regulation of the kidney in reference and adaptive injury states. We established a comprehensive and spatially-anchored epigenomic atlas to define the kidney's active, silent, and regulatory accessible chromatin regions across the genome. Using this atlas, we noted distinct control of adaptive injury in different epithelial cell types. A proximal tubule cell transcription factor network of ELF3 , KLF6 , and KLF10 regulated the transition between health and injury, while in thick ascending limb cells this transition was regulated by NR2F1 . Further, combined perturbation of ELF3 , KLF6 , and KLF10 distinguished two adaptive proximal tubular cell subtypes, one of which manifested a repair trajectory after knockout. This atlas will serve as a foundation to facilitate targeted cell-specific therapeutics by reprogramming gene regulatory networks.

Roles of Krüppel-Like Transcription Factors KLF6 and KLF15 in Proximal Tubular Metabolism

Members of the Krüppel-like family of transcription factors are widely expressed, including in the kidney. Expression of some KLFs changes in acute kidney injury, and this may be adaptive or maladaptive, and result in effects on various cellular pathways. This mini-review will highlight the roles of KLF6 and KLF15 in control of proximal tubular cell metabolism.

Role of microRNAs in programmed cell death in renal diseases: A review

MicroRNAs (miRNAs) regulate gene expression involving kidney morphogenesis and cell proliferation, apoptosis, differentiation, migration, invasion, immune evasion, and extracellular matrix remodeling. Programmed cell death (PCD) is mediated and regulated by specific genes and a wealth of miRNAs, which participate in various pathological processes. Dysregulation of miRNAs can disrupt renal development and induce the onset and progression of various renal diseases. An in-depth understanding of how miRNAs regulate renal development and diseases is indispensable to comprehending how they can be used in new diagnostic and therapeutic approaches. However, the mechanisms are still insufficiently investigated. Hence, we review the current roles of miRNA-related signaling pathways and recent advances in PCD research and aim to display the potential crosstalk between miRNAs and PCD. The prospects of miRNAs as novel biomarkers and therapeutic targets are also described, which might provide some novel ideas for further studies.

Human bone marrow mesenchymal stem cell-derived extracellular vesicles reduce inflammation and pyroptosis in acute kidney injury via miR-223-3p/HDAC2/SNRK

OBJECTIVE

Bone marrow mesenchymal stem cell (BMSC)-derived extracellular vesicles (EVs) have been demonstrated as a potential therapeutic agent in acute kidney injury (AKI). However, little is known about the mechanisms of action of BMSC-derived EVs in AKI. Based on this, our research was designed to investigate the mechanism behind BMSC-derived EVs controlling inflammation and pyroptosis during AKI.

METHODS

Peripheral blood from AKI patients was used for detection of microRNA (miR)-223-3p, HDAC2, and SNRK expression. An AKI rat model was established, and HK-2 cell injury was induced by lipopolysaccharide (LPS) to establish a cellular model. Co-culture with BMSC-derived EVs and/or gain- and loss-of-function assays were conducted in LPS-treated HK-2 to evaluate the functions of BMSCs-EVs, miR-223-3p, HDAC2, and SNRK. AKI rats were simultaneously injected with EVs and short hairpin RNAs targeting SNRK. The interactions among miR-223-3p, HDAC2, and SNRK were evaluated by RIP, ChIP, and dual-luciferase gene reporter assays.

RESULTS

Patients with AKI had low miR-223-3p and SNRK expression and high HDAC2 expression in peripheral blood. Mechanistically, miR-223-3p targeted HDAC2 to accelerate SNRK transcription. In LPS-treated HK-2 cells, BMSCs-EVs overexpressing miR-223-3p increased cell viability and diminished cell apoptosis, KIM-1, LDH, IL-1β, IL-6, TNF-α, NLRP3, ASC, cleaved caspase-1, and IL-18 expression, and GSDMD cleavage, which was nullified by HDAC2 overexpression or SNRK silencing. In AKI rats, BMSCs-EV-shuttled miR-223-3p reduced CRE and BUN levels, apoptosis, inflammation, and pyroptosis, which was abrogated by SNRK silencing.

CONCLUSION

Conclusively, BMSC-derived EV-encapsulated miR-223-3p mitigated AKI-induced inflammation and pyroptosis by targeting HDAC2 and promoting SNRK transcription.