LncRNA MALAT1-deficiency restrains lipopolysaccharide (LPS)-induced pyroptotic cell death and inflammation in HK-2 cells by releasing microRNA-135b-5p

LncRNA MALAT1 regulates cigarette smoke induced airway inflammation by modulating miR-30a-5p/JNK signaling pathway

Chronic airway inflammation induced by cigarette smoke (CS) plays an essential role in the pathogenesis of chronic obstructive pulmonary disease (COPD). MALAT1 is involved in a variety of inflammatory disorders. However, studies focusing on the interaction between MALAT1 and CS-induced airway inflammation remain unknown. The present study investigated the effects and mechanisms of MALAT1 in CS-induced airway inflammation in the pathogenesis of COPD. RT-qPCR was employed to determine the mRNA levels of MALAT1, miR-30a-5p and inflammatory cytokines. Protein concentrations of IL-1β and IL-6 in cell culture supernatant and mouse bronchoalveolar lavage fluid (BALF) were assessed by ELISA assay kits. Dual-luciferase reporter assay was conducted to verify the interaction between MALAT1 and miR-30a-5p. The protein expression of JNK and p-JNK was determined by western blot (WB). MALAT1 was highly expressed in cigarette smoke extract (CSE)-treated human bronchial epithelial cells (HBECs) and COPD mice lung tissues. Knockdown of MALAT1 significantly alleviate CS-induced inflammatory response. MALAT1 directly interacted with miR-30a-5p and knockdown of miR-30a-5p significantly inhibit the protective effects of MALAT1 silencing after CS exposure. Additionally, our results showed that miR-30a-5p could regulate inflammation via modulating the activation of JNK signaling pathway. Moreover, our results demonstrated MALAT1 could activate JNK signaling pathway by sponging miR-30a-5p. Our results demonstrated MALAT1 promotes CS-induced airway inflammation by inhibiting the activation of JNK signaling pathway via sponging miR-30a-5p.

Research Progress of Pyroptosis in Diabetic Kidney Disease

Pyroptosis, known as one typical mode of programmed cell death, is generally characterized by the cleaved gasdermin family (GSDMs) forming pores in the cell membrane and inducing cell rupture, and the activation of aspartate-specific proteases (caspases) has also been found during this process. Diabetic Kidney Disease (DKD) is caused by the complication of diabetes in the kidney, and the most important kidney's function, Glomerular Filtration Rate (GFR), happens to drop to less than 90% of its usual and even lead to kidney failure in severe cases. The persistent inflammatory state induced by high blood glucose implies the key pathology of DKD, and growing evidence shows that pyroptosis serves as a significant contributor to this chronic immune-mediated inflammatory disorder. Currently, the expanded discovery of GSDMs, pyroptosis, and its association with innate immunity has been more attractive, and overwhelming research is needed to sort out the implication of pyroptosis in DKD pathology. In this review, we comb both classical studies and newly founds on pyroptosis, prick off the novel awakening of pyroptosis in DKD, and center on the significance of pyroptosis in DKD treatment, aiming to provide new research targets and treatment strategies on DKD.

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

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

Long Non-Coding RNA MALAT1 Protects Against Spinal Cord Injury via Suppressing microRNA-125b-5p Mediated Microglial M1 Polarization, Neuroinflammation, and Neural Apoptosis

Our previous studies have discovered that long non-coding RNA (lncRNA) MALAT1 and its target microRNA-125b-5p (miR-125b-5p) are implicated in neurological diseases via regulating neuroinflammation and neuronal injury. This study aimed to further explore the relationship between lncRNA MALAT1 and miR-125b-5p, as well as their effect on microglial activation, neuroinflammation, and neural apoptosis in spinal cord injury (SCI). Primary microglia from Sprague Dawley rats were stimulated with lipopolysaccharide (LPS). Then, microglia were transfected with lncRNA MALAT1 overexpression or knock-down adenovirus-associated virus with or without miR-125b-5p mimic. The culture medium of microglia was incubated with primary neurons. SCI rats were established for in vivo validation. LncRNA MALAT1 expression was reduced by LPS treatment in a dose-dependent manner. LncRNA MALAT1 overexpression suppressed the microglial M1 polarization (decreased iNOS but increased ARG1), neuroinflammation (declined PTGS2, TNF-α, IL-1β, and IL-6), and microglia-induced neural apoptosis (lower TUNEL positive cells and C-caspase3 but higher BCL2) under LPS treatment; its knock-down displayed the opposite trend. Moreover, lncRNA MALAT1 directly bound to and negatively regulated miR-125b-5p. MiR-125b-5p mimic promoted microglial M1 polarization, neuroinflammation, and microglia-induced neural apoptosis following LPS treatment; also, it could attenuate the effect of lncRNA MALAT1. Further in vivo study displayed that lncRNA MALAT1 overexpression elevated the Basso-Beattie-Bresnahan motor function score and improved neural injury. Also, in vivo validation indicated a similar effect of lncRNA MALAT1 on microglial polarization and neuroinflammation as in vitro. LncRNA MALAT1 improves SCI recovery via miR-125b-5p mediated microglial M1 polarization, neuroinflammation, and neural apoptosis.

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.

Exploring the Therapeutic Significance of microRNAs and lncRNAs in Kidney Diseases

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two crucial classes of transcripts that belong to the major group of non-coding RNAs (ncRNAs). These RNA molecules have significant influence over diverse molecular processes due to their crucial role as regulators of gene expression. However, the dysregulated expression of these ncRNAs constitutes a fundamental factor in the etiology and progression of a wide variety of multifaceted human diseases, including kidney diseases. In this context, over the past years, compelling evidence has shown that miRNAs and lncRNAs could be prospective targets for the development of next-generation drugs against kidney diseases as they participate in a number of disease-associated processes, such as podocyte and nephron death, renal fibrosis, inflammation, transition from acute kidney injury to chronic kidney disease, renal vascular changes, sepsis, pyroptosis, and apoptosis. Hence, in this current review, we critically analyze the recent findings concerning the therapeutic inferences of miRNAs and lncRNAs in the pathophysiological context of kidney diseases. Additionally, with the aim of driving advances in the formulation of ncRNA-based drugs tailored for the management of kidney diseases, we discuss some of the key challenges and future prospects that should be addressed in forthcoming investigations.

Puerarin alleviates chronic renal failure-induced pyroptosis in renal tubular epithelial cells by targeting miR-342-3p/TGF-β/SMAD axis

BACKGROUND

Chronic renal failure (CRF) is the result of kidney damage. Puerarin is a flavonoid with specific nephroprotective effect, but its effect on CRF needs further research. This study explored the effect of puerarin on CRF and the potential molecular mechanism.

METHODS

Adenine was used to establish an in vivo CRF model in rats, and rats were intragastrically administered with puerarin at a dose of 400 mg/kg body weight once a day from day 1 to day 28. Hematoxylin and eosin (HE) and Masson staining were used to observe the morphology and fibrosis of kidney tissue. Lipopolysaccharide (LPS) (400 ng/mL)/H2O2 (200 µM) was applied to human kidney 2 (HK-2) cells to construct an in vitro CRF model. Enzyme-linked immunosorbent assay (ELISA) was performed to validate interleukin (IL)-1β and IL-18 levels. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was performed to detect microRNA (miR)-342-3p levels. Transforming growth factor beta (TGF-β)1, SMAD2, SMAD3, and pyroptosis marker proteins were detected by Western blot. The interaction between miR-342-3p and TGF-β/SMAD was determined by a dual-luciferase reporter gene assay. Cell Counting Kit-8 (CCK-8) assay was utilized to determine cell viability.

RESULTS

In the CRF model, puerarin alleviated renal injury and fibrosis and reduced creatinine (Cr) and blood urea nitrogen (BUN) levels. At the same time, miR-342-3p was downregulated, while the TGF-β/SMAD axis was activated and levels of IL-1β and IL-18 were increased. After treatment of CRF rats with puerarin, the expression level of miR-342-3p was increased, the TGF-β/SMAD axis was inhibited, and the secretion of IL-1β and IL-18 was decreased. MiR-342-3p directly bound to and negatively regulated the expression of TGF-β1, SMAD2, and SMAD3. In the in vitro CRF model, miR-342-3p inhibited HK-2 cell pyroptosis by inhibiting the TGF-β/SMAD axis.

CONCLUSION

Puerarin reduced renal injury and pyroptosis in CRF rats by targeting the miR-342-3p/TGF-β/SMAD axis.

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.

Downregulation of circ-ZNF644 alleviates LPS-induced HK2 cell injury via miR-335-5p/HIPK1 axis

Circular RNA (circRNA) has been confirmed to be involved in regulating sepsis-induced acute kidney injury (AKI). Our research aims to explore circ-ZNF644 role in the development of sepsis-induced AKI. Lipopolysaccharide (LPS) was used to induce kidney tubular epithelial cell (HK2) injury. ELISA assay was performed to measure the concentrations of inflammation factors. Cell functions were determined by cell counting kit 8 assay, EdU assay and flow cytometry. Protein expression was evaluated by Western blot analysis. Quantitative real-time PCR was used to detect relative expression of circ-ZNF644, miR-335-5p and homeodomain-interacting protein kinase 1 (HIPK1). RNA interaction was confirmed by dual-luciferase reporter assay and RIP assay. LPS enhanced HK2 cell inflammation, oxidative stress, apoptosis, and reduced proliferation. Circ-ZNF644 was overexpressed in sepsis-induced AKI patients. Circ-ZNF644 knockdown suppressed LPS-induced HK2 cell injury, and this effect could be revoked by miR-335-5p inhibitor. MiR-335-5p was sponged by circ-ZNF644, and its expression was downregulated in sepsis-induced AKI patients. HIPK1 was targeted by miR-335-5p, and its expression could be suppressed by circ-ZNF644 knockdown. MiR-335-5p had an inhibition effect on HK2 cell injury induced by LPS, and HIPK1 overexpression could reverse this effect. Circ-ZNF644 knockdown relieved LPS-induced HK2 cell injury through the miR-335-5p/HIPK1 axis, confirming that circ-ZNF644 contributed to sepsis-induced AKI.

Kidney diseases and long non-coding RNAs in the limelight

The most extensively and well-investigated sequences in the human genome are protein-coding genes, while large numbers of non-coding sequences exist in the human body and are even more diverse with more potential roles than coding sequences. With the unveiling of non-coding RNA research, long-stranded non-coding RNAs (lncRNAs), a class of transcripts >200 nucleotides in length primarily expressed in the nucleus and rarely in the cytoplasm, have drawn our attention. LncRNAs are involved in various levels of gene regulatory processes, including but not limited to promoter activity, epigenetics, translation and transcription efficiency, and intracellular transport. They are also dysregulated in various pathophysiological processes, especially in diseases and cancers involving genomic imprinting. In recent years, numerous studies have linked lncRNAs to the pathophysiology of various kidney diseases. This review summarizes the molecular mechanisms involved in lncRNAs, their impact on kidney diseases, and associated complications, as well as the value of lncRNAs as emerging biomarkers for the prevention and prognosis of kidney diseases, suggesting their potential as new therapeutic tools.

miR-181a-5p Inhibits Pyroptosis in Sepsis-Induced Acute Kidney Injury through Downregulation of NEK7

Sepsis is a life-threatening organ dysfunction caused by the uncontrolled inflammation, easily affecting the kidney. Sepsis-induced acute kidney injury (S-AKI) has high morbidity and mortality, of which the pathophysiological mechanisms have not been completely illuminated, leading to nonspecific therapies. Specific microRNAs were related with the pathogenesis of AKI. However, only limited studies focused on the pyroptosis in the context of S-AKI. The in vitro LPS-induced HK-2 cell model and in vivo CLP-induced mouse model were established. qRT-PCR, Western blot, ELISA, and RNA pulldown were used for expression examination. Multiple biological databases were used for miRNA screening. H&E staining and IHC staining were performed. The LPS-induced HK-2 cells showed significantly increased (P < 0.01) fluorescence intensity of N-GSDMD and ASC compared with the HK-2 cells. The expression of NLRP3, NEK7, ASC, active caspase-1, and N-GSDMD was significantly enhanced (P < 0.05) and the inflammatory factors including IL-18, IL-1β, and THF-α were all increased in LPS-induced HK-2 cells and CLP-induced mice. Renal edema, serum Cr and BUN, and expression of KIM-1 and NGAL were significantly higher (P < 0.05) in CLP-induced S-AKI mice than the sham group. miR-101-3p, miR-144-3p, miR-181a-5p, miR-4262, and miR-513b-5p could inhibit NEK7. NEK7 is an interacting protein of miRNA-181a-5p. miR-181a-5p inhibits pyroptosis of the LPS-induced HK-2 cells through downregulation of NEK7. Pyroptosis of HK-2 cells promotes inflammation. miR-181a-5p inhibits pyroptosis through downregulation of NEK7 in LPS-induced HK-2 cells and CLP-induced mice. Our study indicated miR-181a-5p as a new potential therapeutic target for S-AKI therapy.

The Intersection of Acute Kidney Injury and Non-Coding RNAs: Inflammation

Acute renal injury (AKI) is a complex clinical syndrome, involving a series of pathophysiological processes, in which inflammation plays a key role. Identification and verification of gene signatures associated with inflammatory onset and progression are imperative for understanding the molecular mechanisms involved in AKI pathogenesis. Non-coding RNAs (ncRNAs), involved in epigenetic modifications of inflammatory responses, are associated with the aberrant expression of inflammation-related genes in AKI. However, its regulatory role in gene expression involves precise transcriptional regulation mechanisms which have not been fully elucidated in the complex and volatile inflammatory response of AKI. In this study, we systematically review current research on the intrinsic molecular mechanisms of ncRNAs that regulate the inflammatory response in AKI. We aim to provide potential research directions and strategies for developing ncRNA-targeted gene therapies as an intervention for the inflammatory damage in AKI.