Down-regulation of LncRNA CRNDE aggravates kidney injury via increasing MiR-181a-5p in sepsis

Diagnostic capacity of miRNAs in neonatal sepsis: a systematic review and meta-analysis

BACKGROUND

Neonatal sepsis is the third leading cause of mortality during the neonatal period, with manifestations atypical and obscure. But the gold standard-blood culture test, requiring 3-5 days, makes it difficult to unveil the final pathogen and leads to the increasing ratio of false-negative results. The empirical method is consulting traditional biomarkers, such as procalcitonin (PCT), C-reactive protein (CRP), and white blood cell count. However, they are not specific for neonate in diagnostic capacity, especially for infants within three days after delivery, so more novel biomarkers are urgently needed to assist diagnosing neonatal sepsis. microRNAs (miRNAs) have been widely studied in recent years for their diagnostic and prognostic values in different diseases and we conducted a meta-analysis of miRNAs on the topic that whether they are potentially novel biomarkers in early detection of neonatal sepsis.

OBJECTIVES

The purpose of the study was to assess whether circulating miRNAs could be used as potential biomarkers for neonatal sepsis, including early and late-onset neonatal sepsis, then calculate their overall accuracy (OA) via meta-analysis.

METHODS

PubMed, Cochrane Library, Embase, Web of Science, Scopus, and Ovid databases were retrieved; data cutoff for this analysis was 15 January 2023. Methodological quality assessment of included studies was performed through the Quality in Prognostic Studies tool. Corresponding 95% confidence interval (95%CI) was calculated to present miRNAs' diagnostic value including the pooled sensitivity (Sen), specificity (Spe), positive or negative likelihood ratios (PLR or NLR), diagnostic odds ratio (DOR), and area under the curve (AUC). Differences in OA between the septic group and non-septic group were compared using Chi-square test.

RESULTS

After identification, 16 records out of 11 selected articles were eligible for systematic review of miRNAs and four records for PCT; the case group for miRNAs included 945 neonatal sepsis cases; contrast group included 190 respiratory tract infections or pneumonia cases, 60 systemic inflammatory response syndrome (SIRS) cases and 559 healthy neonates. The pooled Sen, Spe, and DOR of miRNAs were 0.87 (95%CI 0.81-0.91), 0.79 (95%CI 0.71-0.85), and 24 (95%CI 12-50), respectively. The pooled Sen, Spe, and DOR of PCT were 0.92 (95%CI 0.83-0.96), 0.64 (95%CI 0.56-0.70), and 20 (95%CI, 7-56), respectively. The OA value of miRNAs was 80.38% and that of PCT was 77.36%, which were not statistically significant difference (p = .13) after the Chi-square test. In addition, no significant publication bias was indicated (p = .92).

CONCLUSIONS

Circulating miRNA levels could be applied as diagnostic biomarkers in neonatal sepsis.

Lipopolysaccharide (LPS)-induced inflammation in RAW264.7 cells is inhibited by microRNA-494-3p via targeting lipoprotein-associated phospholipase A2

BACKGROUND

Gram-negative bacterial lipopolysaccharide (LPS) is a major component of inflammation and plays a key role in the pathogenesis of sepsis. According to our previous study, the expression of lipoprotein-associated phospholipase A2 (Lp-PLA2) is significantly upregulated in septic patients and is positively correlated with the severity of this disease. Herein, we investigated the potential roles of Lp-PLA2-targeting microRNAs (miRNAs) in LPS-induced inflammation in murine mononuclear macrophages (RAW264.7 cells).

METHODS

In LPS-stimulated RAW264.7 cells, Lp-PLA2 was confirmed to be expressed during the inflammatory response. The function of microRNA-494-3p (miR-494-3p) in the LPS-induced inflammatory response of RAW264.7 cells was determined by the transfection of a miR-494-3p mimic or inhibitor in vitro.

RESULTS

Compared to the control, LPS induced a significant increase in the Lp-PLA2 level, which was accompanied by the release of inflammatory mediators. The bioinformatics and qRT‒PCR results indicated that the miR-494-3p level was associated with Lp-PLA2 expression in the LPS-induced inflammatory response of RAW264.7 cells. Dual-luciferase reporter assay results confirmed that the 3'-UTR of Lp-PLA2 was a functional target of microRNA-494-3p. During the LPS-induced inflammatory response of RAW264.7 cells, targeting Lp-PLA2 and transfecting miR-494-3p mimics significantly upregulated the expression of miR-494-3p, leading to a reduction in the release of inflammatory factors and conferring a protective effect on LPS-stimulated RAW264.7 cells.

CONCLUSION

By targeting Lp-PLA2, miR-494-3p suppresses Lp-PLA2 secretion, thereby alleviating LPS-induced inflammation, which indicates that miR-494-3p may be a potential target for sepsis treatment.

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.

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 noncoding RNA: An emerging diagnostic and therapeutic target in kidney diseases

Long noncoding RNAs (lncRNAs) have critical roles in the development of many diseases including kidney disease. An increasing number of studies have shown that lncRNAs are involved in kidney development and that their dysregulation can result in distinct disease processes, including acute kidney injury, chronic kidney disease, and renal cell carcinoma. Understanding the roles of lncRNAs in kidney disease may provide new diagnostic and therapeutic opportunities in the clinic. This review provides an overview of lncRNA characteristics, and biological function and discusses specific studies that provide insight into the function and potential application of lncRNAs in kidney disease treatment.

Human umbilical cord mesenchymal stromal cell small extracellular vesicle transfer of microRNA-223-3p to lung epithelial cells attenuates inflammation in acute lung injury in mice

BACKGROUND

Acute lung injury (ALI), manifested as strong pulmonary inflammation and alveolar epithelial damage, is a life-threatening disease with high morbidity and mortality. Small extracellular vesicles (sEVs), secreted by multiple types of cells, are critical cellular communication mediators and can inhibit inflammation by transferring bioactive molecules, such as microRNAs (miRNAs). Thus, we hypothesized that sEVs derived from mesenchymal stromal cells (MSC sEVs) could transfer miRNAs to attenuate inflammation of lung epithelial cells during ALI.

METHODS

C57BL/6 male mice were intratracheally administered LPS (10 mg/kg). Six hours later, the mice were randomly administered with MSC sEVs (40 µg per mouse in 150 µl of saline), which were collected by ultracentrifugation. Control group received saline administration. After 48 h, the mice were sacrificed to evaluate pulmonary microvascular permeability and inflammatory responses. In vitro, A549 cells and primary human small airway epithelial cells (SAECs) were stimulated with LPS with or without MSC sEVs treatment.

RESULTS

In vitro, MSC sEVs could also inhibit the inflammation induced by LPS in A549 cells and SAECs (reducing TNF-α, IL-1β, IL-6 and MCP-1). Moreover, MSC sEV treatment improved the survival rate, alleviated pulmonary microvascular permeability, and inhibited proinflammatory responses (reducing TNF-α, IL-1β, IL-6 and JE-1) in ALI mice. Notably, miR-223-3p was found to be served as a critical mediator in MSC sEV-induced regulatory effects through inhibition of poly (adenosine diphosphate-ribose) polymerase-1 (PARP-1) in lung epithelial cells.

CONCLUSIONS

Overall, these findings suggest that MSC sEVs may offer a novel promising strategy for ALI.

Integrated analysis of mRNA-seq and miRNA-seq reveals the potential roles of Egr1, Rxra and Max in kidney stone disease

Nephrolithiasis is one of the most common and frequent urologic diseases worldwide. The molecular mechanism of kidney stone formation is complex and remains to be illustrated. Transcript factors (TFs) that influenced the expression pattern of multiple genes, as well as microRNAs, important posttranscriptional modulators, play vital roles in this disease progression. Datasets of nephrolithiasis mice and kidney stone patients were acquired from Gene Expression Omnibus repository. TFs were predicted from differentially expressed genes by RcisTarget. The target genes of differential-expressed microRNAs were predicted by miRWalk. MicroRNA-mRNA network and PPI network were constructed. Functional enrichment analysis was performed via Metascape and Cytoscape identified hub genes. The assay of quantitative real-time PCR (q-PCR) and immunochemistry and the datasets of oxalate diet-induced nephrolithiasis mice kidneys and kidney stone patients' samples were utilized to validate the bioinformatic results. We identified three potential key TFs (Egr1, Rxra, Max), which can be modulated by miR-181a-5p, miR-7b-3p and miR-22-3p, respectively. The TFs and their regulated hub genes influenced the progression of nephrolithiasis via altering the expression of genes enriched in the functions of fibrosis, cell proliferation and molecular transportation and metabolism. The expression changes of transcription factors were consistent in q-PCR and immunochemistry results. For regulated hub genes, they showed consistent expression changes in oxalate diet-induced nephrolithiasis mice model and human kidneys with stones. The identified and verified three TFs, which may be modulated by microRNAs in nephrolithiasis disease progression, mainly influence biological processes responding to fibrosis, proliferation and molecular transportation and metabolism. The transcript influence showed consistency in multiple nephrolithiasis mice models and kidney stone patients.

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.

Mechanisms underlying the therapeutic effects of 4-octyl itaconate in treating sepsis based on network pharmacology and molecular docking

Objective: Through network pharmacology and molecular docking technology, the hub genes, biological functions, and signaling pathways of 4-Octyl itaconate (4-OI) against sepsis were revealed.

Methods: Pathological targets of sepsis were screened using GeneCards and GEO databases. Similarly, the pharmacological targets of 4-OI were obtained through Swiss TargetPrediction (STP), Similarity ensemble approach (SEA), and TargetNet databases. Then, all the potential targets of 4-OI anti-sepsis were screened by the online platform Draw Venn diagram, and the hub genes were screened by Cytoscape software. The identified hub genes were analyzed by GO and KEGG enrichment analysis, protein interaction (PPI) network, and molecular and docking technology to verify the reliability of hub gene prediction, further confirming the target and mechanism of 4-OI in the treatment of sepsis.

Results: After the target screening of 4-OI and sepsis, 264 pharmacological targets, 1953 pathological targets, and 72 genes related to 4-OI anti-sepsis were obtained, and eight hub genes were screened, namely MMP9, MMP2, SIRT1, PPARA, PTPRC, NOS3, TLR2, and HSP90AA1. The enrichment analysis results indicated that 4-OI might be involved in regulating inflammatory imbalance, immunosuppression, and oxidative stress in developing sepsis. 4-OI protects multiple organ dysfunction in sepsis by acting on hub genes, and MMP9 is a reliable gene for the prognosis and diagnosis of sepsis. The molecular docking results showed that 4-OI binds well to the hub target of sepsis.

Conclusion: 4-OI plays an antiseptic role by regulating MMP9, MMP2, SIRT1, PPARA, PTPRC, NOS3, TLR2 and HSP90AA1. These Hub genes may provide new insights into follow-up research on the target of sepsis treatment.

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.

CircZNF644 aggravates lipopolysaccharide-induced HK-2 cell impairment via the miR-140-5p/MLKL axis

Circular RNAs (circRNAs) play vital roles in human diseases, including acute kidney injury (AKI). In this paper, we focused on the effect of circRNA zinc finger protein 644 (circZNF644) on AKI cell model progression. qRT-PCR was conducted for the levels of circZNF644, ZNF644, miR-140-5p and mixed lineage kinase domain like pseudokinase (MLKL). RNase R assay, actinomycin D assay and subcellular fraction analysis were conducted to analyze the features of circZNF644. CCK-8 assay and EdU assay were used to explore cell proliferation. Flow cytometry analysis was conducted to analyze cell cycle and cell apoptosis. Western blot assay was executed for protein levels. ELISA was performed for the levels of inflammatory cytokines. The relationships among circZNF644, miR-140-5p and MLKL were analyzed by dual-luciferase reporter assay and RIP assay. CircZNF644 was upregulated in LPS-stimulated HK-2 cells. LPS-mediated inhibitory effects on cell proliferation and cell cycle and promotional effects on apoptosis and inflammation were reversed by circZNF644 knockdown. CircZNF644 directly interacted with miR-140-5p and MLKL was the target gene of miR-140-5p. The impact of circZNF644 knockdown on HK-2 cell injury was relieved by miR-140-5p inhibition. Moreover, miR-140-5p enhancement alleviated LPS-triggered HK-2 cell damage, while MLKL elevation reversed the effect. CircZNF644 knockdown protected HK-2 cells from LPS-induced injury by altering miR-140-5p/MLKL pathway, suggesting that circZNF644 may be a hopeful therapeutic target for AKI.

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.

Non-Coding RNAs in Sepsis-Associated Acute Kidney Injury

Sepsis is a systemic inflammatory response caused by a severe infection that leads to multiple organ damage, including acute kidney injury (AKI). In intensive care units (ICU), the morbidity and mortality associated with sepsis-associated AKI (SA-AKI) are gradually increasing due to lack of effective and early detection, as well as proper treatment. Non-coding RNAs (ncRNAs) exert a regulatory function in gene transcription, RNA processing, post-transcriptional translation, and epigenetic regulation of gene expression. Evidence indicated that miRNAs are involved in inflammation and programmed cell death during the development of sepsis-associated AKI (SA-AKI). Moreover, lncRNAs and circRNAs appear to be an essential regulatory mechanism in SA-AKI. In this review, we summarized the molecular mechanism of ncRNAs in SA-AKI and discussed their potential in clinical diagnosis and treatment.

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.

Long non-coding RNA metastasis-related lung adenocarcinoma transcript 1 (MALAT1) forms a negative feedback loop with long non-coding RNA colorectal neoplasia differentially expressed (CRNDE) in sepsis to regulate lung cell apoptosis

It has been reported that long non-coding RNAs (lncRNAs) metastasis-related lung adenocarcinoma transcript 1 (MALAT1) and colorectal neoplasia differentially expressed (CRNDE) play opposite roles in sepsis. Therefore, we explored their potential interaction with sepsis. To this end, we determined MALAT1 and CRNDE levels using RT-qPCR in plasma samples collected from healthy controls (n = 60) and sepsis patients (n = 60) before and after treatment and the effects of MALAT1 and CRNDE overexpression in human bronchial epithelial cells (HBEpCs) on the expression of each other and HBEpC apoptosis. RT-qPCR analyses showed that MALAT1 was upregulated, while CRNDE was downregulated in sepsis and overexpression of MALAT1 and CRNDE downregulated the expression of each other. After proper treatment, MALAT1 was downregulated and CRNDE was upregulated in sepsis. Lipopolysaccharides (LPS) treatment of HBEpCs upregulated MALAT1 and downregulated CRNDE. Cell apoptosis analysis showed that MALAT1 overexpression promoted, while CRNDE overexpression inhibited LPS-induced HBEpC apoptosis. Moreover, CRNDE overexpression attenuated the effects of MALAT1 overexpression. Overall, MALAT1 might form a negative feedback loop with CRNDE in sepsis to regulate lung cell apoptosis.

miR-23a-3p inhibits sepsis-induced kidney epithelial cell injury by suppressing Wnt/β-catenin signaling by targeting wnt5a

The present study was designed to investigate the involvement of miR-23a-3p in the progression of sepsis-induced acute kidney injury (AKI). The expression levels of miR-23a-3p and wnt5a in sepsis-induced AKI patients and lipopolysaccharide (LPS)-treated HK-2 cells were detected by real-time PCR and western blotting. Then, the effects of miR-23a-3p overexpression on cell viability, apoptosis, and inflammatory cytokines secretion in LPS-stimulated HK-2 cells were investigated. Moreover, luciferase reporter assay was performed to confirm the regulatory relationship between miR-23a-3p and wnt5a. Whether miR-23a-3p regulated the activation of Wnt/β-catenin signaling was also explored. mR-23a-3p was lowly expressed in the serum of patients with sepsis-associated AKI and in LPS-treated HK-2 cells. In addition, the overexpression of miR-23a-3p restrained LPS-induced proliferation inhibition and promotion of apoptosis and cytokine production in HK-2 cells. Moreover, wnt5a was identified as a target of miR-23a-3p, which could be negatively regulated by miR-23a-3p. Overexpression of miR-23a-3p suppressed the activation of Wnt/β-catenin signaling in LPS-treated HK-2 cells, which was markedly reversed by wnt5a upregulation. Upregulation of miR-23a-3p may alleviate LPS-induced cell injury by targeting wnt5a and inactivating Wnt/β-catenin pathway, which may serve as a novel therapeutic target for sepsis-associated AKI.

Regulatory Role of Non-Coding RNAs on Immune Responses During Sepsis

Sepsis is resulted from a systemic inflammatory response to bacterial, viral, or fungal agents. The induced inflammatory response by these microorganisms can lead to multiple organ system failure with devastating consequences. Recent studies have shown altered expressions of several non-coding RNAs such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) during sepsis. These transcripts have also been found to participate in the pathogenesis of multiple organ system failure through different mechanisms. NEAT1, MALAT1, THRIL, XIST, MIAT and TUG1 are among lncRNAs that participate in the pathoetiology of sepsis-related complications. miR-21, miR-155, miR-15a-5p, miR-494-3p, miR-218, miR-122, miR-208a-5p, miR-328 and miR-218 are examples of miRNAs participating in these complications. Finally, tens of circRNAs such as circC3P1, hsa_circRNA_104484, hsa_circRNA_104670 and circVMA21 and circ-PRKCI have been found to affect pathogenesis of sepsis. In the current review, we describe the role of these three classes of noncoding RNAs in the pathoetiology of sepsis-related complications.

CircVMA21 ameliorates lipopolysaccharide (LPS)-induced HK-2 cell injury depending on the regulation of miR-7-5p/PPARA

Accumulating evidence suggests that circular RNAs (circRNAs) are implicated in diverse human diseases, including sepsis-engendered acute kidney injury (AKI). In this study, we investigated the functions of circRNA vacuolar ATPase assembly factor VMA21 (circVMA21) in septic AKI through establishing septic AKI in vitro model. Quantitative real-time polymerase chain reaction (qRT-PCR) assay was adopted to determine the levels of circVMA21, microRNA-7-5p (miR-7-5p) and peroxisome proliferator activated receptor alpha (PPARA) mRNA. Cell Counting Kit-8 (CCK-8) assay and flow cytometry analysis were conducted to evaluate cell viability and apoptosis. Western blot assay was used for protein levels. Enzyme-linked immunosorbent assay (ELISA) was performed for the secretion of inflammatory cytokines. The levels of oxidative stress markers were examined with specific commercial kits. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were utilized the analyse the relationships among circVMA21, miR-7-5p and PPARA. CircVMA21 was reduced in sepsis patients' serums and LPS-stimulated HK2 cells. CircVMA21 overexpression reversed the suppressive effect on cell viability and the promotional effects on cell apoptosis, inflammation and oxidative stress in HK2 cells mediated by LPS. CircVMA21 was identified as the sponge for miR-7-5p. MiR-7-5p overexpression abrogated the impacts of circVMA21 elevation on cell viability, apoptosis, inflammation and oxidative stress in LPS-stimulated HK2 cells. MiR-7-5p directly targeted PPARA, and miR-7-5p inhibition ameliorated LPS-induced HK2 cell damage by targeting PPARA. CircVMA21 overexpression alleviated LPS-stimulated HK2 cell damage through the regulation of miR-7-5p/PPARA.

Long noncoding RNAs Colorectal Neoplasia Differentially Expressed and taurine-upregulated gene 1 are downregulated in sepsis and positively regulate each other to suppress the apoptosis of cardiomyocytes

Long noncoding RNAs (lncRNAs) Colorectal Neoplasia Differentially Expressed (CRNDE) and taurine-upregulated gene 1 (TUG1) play similar roles in sepsis, indicating the existence of the crosstalk between them. Sepsis is a major cause of injuries in heart, which are related to high mortality rates. This study was therefore carried out to analyze the potential crosstalk between CRNDE and TUG1 in sepsis, with a focus on sepsis-induced cell apoptosis in heart. Expression of CRNDE and TUG1 was analyzed with RT-qPCR. Correlations between them were analyzed by Pearson’s correlation coefficient. CRNDE and TUG1 were overexpressed in cardiomyocytes to determine the relationship between them. The roles of CRNDE and TUG1 in regulating the apoptosis of cardiomyocytes were explored by cell apoptosis assay. We found that both CRNDE and TUG1 were downregulated in sepsis. In cardiomyocytes, LPS treatment resulted in the downregulation of CRNDE and TUG1. Overexpression of CRNDE and TUG1 in cardiomyocytes increased the expression levels of each other. Under lipopolysaccharide (LPS) treatment, decreased apoptosis rates of cardiomyocytes were observed after CRNDE and TUG1 overexpression. CRNDE and TUG1 co-overexpression showed a stronger effect. In conclusion, CRNDE and TUG1 are downregulated in sepsis and they positively regulate each other to suppress the apoptosis of cardiomyocytes.

LncRNA KCNQ1OT1 (potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1) aggravates acute kidney injury by activating p38/NF-κB pathway via miR-212-3p/MAPK1 (mitogen-activated protein kinase 1) axis in sepsis

Acute kidney injury (AKI), a common complication of sepsis, is characterized by a rapid loss of renal excretory function. A variety of etiologies and pathophysiological processes may contribute to AKI. Previously, mitogen-activated protein kinase 1 (MAPK1) was reported to regulate cellular processes in various sepsis-associated diseases. The current study aimed to further explore the biological function and regulatory mechanism of MAPK1 in sepsis-induced AKI. In our study, MAPK1 exhibited high expression in the serum of AKI patients. Functionally, knockdown of MAPK1 suppressed inflammatory response, cell apoptosis in response of lipopolysaccharide (LPS) induction in HK-2 cells. Moreover, MAPK1 deficiency alleviated renal inflammation, renal dysfunction, and renal injury in vivo. Mechanistically, MAPK1 could activate the downstream p38/NF-κB pathway. Moreover, long noncoding RNA potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1 (KCNQ1OT1) was identified to serve as a competing endogenous RNA for miR-212-3p to regulate MAPK1. Finally, rescue assays indicated that the inhibitory effect of KCNQ1OT1 knockdown on inflammatory response, cell apoptosis, and p38/NF-κB pathway was reversed by MAPK1 overexpression in HK-2 cells. In conclusion, KCNQ1OT1 aggravates acute kidney injury by activating p38/NF-κB pathway via miR-212-3p/MAPK1 axis in sepsis. Therefore, KCNQ1OT may serve as a potential biomarker for the prognosis and diagnosis of AKI patients.

LncRNA-Cox2 regulates macrophage polarization and inflammatory response through the CREB-C/EBPβ signaling pathway in septic mice

LncRNA-Cox2 has been reported to regulate macrophage polarization, and the activation of macrophages is a major participant in the pathogenesis of sepsis. Therefore, we explored whether lncRNA-Cox2 was involved in the progression of sepsis. In this study, we established a cecal ligation and puncture (CLP) mouse model and found that silencing lncRNA-Cox2 in CLP mice improved the 7-day survival rate, and alleviated the increase of blood bacterial burdens, systemic inflammatory response, and pulmonary dysfunction induced by CLP. Besides, interference with lncRNA-Cox2 declined the percentage of M1 macrophages and increased the percentage of M2 macrophages in the spleens of CLP mice. In vitro, the knockdown of lncRNA-Cox2 suppressed LPS-induced inflammation and M1 macrophage marker expression, and promoted M2 macrophage marker expression in primary peritoneal macrophages and RAW264.7 cells. Moreover, lncRNA-Cox2 induced CREB phosphorylation by binding to CREB, and increased phosphorylated-CREB enrichment in the C/EBPβ promoter region, so as to promote C/EBPβ transcription, thereby activating the CREB-C/EBPβ cascade. In addition, overexpressing lncRNA-Cox2 enhanced the effect of LPS on inflammation and macrophage polarization, which was reversed by treatment with 666-15 (an inhibitor of CREB). In conclusion, silencing lncRNA-Cox2 restrained the progression of sepsis in mice by modulating macrophage polarization and inflammatory response through suppressing CREB-C/EBPβ pathway.

LncRNA CRNDE Exacerbates IgA Nephropathy Progression by Promoting NLRP3 Inflammasome Activation in Macrophages

BACKGROUND

Activation of NLRP3 inflammasome in macrophages contributes greatly to IgA nephropathy (IgAN) progression. This study intended to investigate the underlying mechanism of NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation in the development of IgAN.

METHODS

We examined the expression levels of colorectal neoplasia differentially expressed (CRNDE), NLRP3 inflammasome-related proteins in peripheral blood mononuclear cells (PBMCs) and J774A.1 cells and detected inflammatory cytokine levels in the serum of IgAN patients and cell supernatants of in vitro IgAN model. RNA pull-down and RNA immunoprecipitation (RIP) experiments were conducted to evaluate the interaction between CRNDE and NLRP3. Then, the ubiquitin level of NLRP3 and its binding ability to TRIM family member 31 (TRIM31) were determined.

RESULTS

Compared with the control group, the expressions of CRNDE and NLRP3 inflammasome-related proteins in PBMCs and J774A.1 cells and levels of IL-1β, TNF-α and IL-12 in serum of IgAN patients and cell supernatants of IgA-IC-induced J774A.1 cells were all increased. CRNDE silencing down-regulated NLRP3 inflammasome-related proteins and the levels of IL-1β, TNF-α and IL-12 in cell supernatants, while NLRP3 overexpression reversed these effects. Additionally, CRNDE could interact with NLRP3 and promote NLRP3 expression. Furthermore, inhibition of CRNDE reduced NLRP3 protein level and promoted TRIM31-mediated NLRP3 ubiquitination and degradation.

CONCLUSION

CRNDE exacerbates IgA nephropathy progression through restraining ubiquitination and degradation of NLRP3 and facilitating NLRP3 inflammasome activation in macrophages.

The role of miR-199b-3p in regulating Nrf2 pathway by dihydromyricetin to alleviate septic acute kidney injury

The pathophysiology of septic acute kidney injury (AKI) is very complex and the fatality is high. Nrf2 is crucial for septic AKI, and dihydromyricetin (DMY) has a protective effect on LPS-induced AKI. We aimed to explore whether DMY could affect Nrf2 pathway by regulating miR-199b-3p and played a protective role in septic AKI. The mouse model was induced by cecal ligation and puncture (CLP) and the cell model was stimulated by LPS. Enzyme-linked immunosorbent assay was conducted to examine MDA, SOD, LDH, GSH, TNF-α, kidney injury molecule 1 (KIM-1), and IL-6 levels. The pathological changes were observed by hematoxylin-eosin staining. The targeted relationship between miR-199b-3p and Nrf2 was verified by a dual-luciferase reporter assay. Levels of SOD, GSH, NQO-1, Nrf2, and HO-1 were decreased, MDA, LDH, TNF-α, IL-6, and KIM-1, and miR-199b-3p were increased in the CLP group and LPS-induced HK-2 cells, while the effect was reversed after DMY treatment. There existed renal tubule cell edema and necrosis, inflammatory cell infiltration in the CLP group, the situation was partially improved by DMY. MiR-199b-3p bound to Nrf2. Nrf2 levels were increased, TNF-α, IL-6, and KIM-1 were decreased after transfected with miR-199b-3p inhibitor, these effects were reversed when co-transfected with si-Nrf2. TNF-α, IL-6, KIM-1, and miR-199b-3p levels were increased; Nrf2, NQO-1, and HO-1 levels were decreased in the LPS + DMY + mimics-miR group. MiR-199b-3p was increased in septic AKI models, DMY might alleviate septic AKI by regulating miR-199b-3p to affect the Nrf2 pathway.

Long noncoding RNAs: A potential target in sepsis-induced cellular disorder

Sepsis, an inflammation-related clinical syndrome, is characterized by disrupted immune homeostasis accompanied by infection and multiple organ dysfunction as determined by the Sequential Organ Failure Assessment (SOFA). Substantial evidence has recently suggested that lncRNAs orchestrate various biological processes in diseases, and lncRNAs play special roles in the diagnosis and management of sepsis. To date, very few reviews have provided clear and comprehensive clues to demonstrate the roles of lncRNAs in the pathogenesis of sepsis. Based on previously published studies, in this review, we summarize the different functions of lncRNAs in sepsis-induced cellular disorders and sepsis-induced organ failure to show the potential roles of lncRNAs in the diagnosis and management of sepsis. We further depict the function of some lncRNAs known to be pivotal regulators in the pathogenesis of sepsis to discuss the underlying molecular events. Additionally, we list and discuss several hotspots in research on lncRNAs, which may be conducive to future lncRNA-targeted therapeutic approaches for sepsis treatment.

Novel lncRNA XLOC_032768 protects against renal tubular epithelial cells apoptosis in renal ischemia-reperfusion injury by regulating FNDC3B/TGF-β1

Renal ischemia–reperfusion injury is a leading cause of acute kidney injury, but its underlying mechanism remains poorly understood and effective therapies are still lacking. Here, we identified lncRNA XLOC_032768 as a novel target in renal ischemia–reperfusion injury by analyzing differentially expressed genes of the transcriptome data. PCR results show that XLOC_032768 was markedly downregulated in the kidney during renal ischemia–reperfusion in mice and in cultured kidney cells during hypoxia. Upon induction in vitro, XLOC_032768 overexpression repressed the expression of fibronectin type III domain containing 3B (FNDC3B) and tubular epithelial cells apoptosis. Administration of XLOC_032768 preserved FNDC3B expression and attenuated renal tubular epithelial cells apoptosis, resulting in protection against kidney injury in mice. Knockdown of FNDC3B markedly reduced the expression of TGF-β1 and apoptosis of renal tubular cells. Thus, XLOC_032768/FNDC3B/TGF-β1signaling pathway in ischemia–reperfusion injury may be targeted for therapy.

Clinical application of non-coding RNAs in sepsis

PURPOSE OF REVIEW

Studies indicating that non-coding RNAs (ncRNAs) play a regulatory role in sepsis are increasing rapidly. This present review summarizes recent publications on the role of microRNAs and long non-coding RNAs (lncRNAs) in sepsis.

RECENT FINDINGS

MicroRNAs (miRNAs) and lncRNAs are being identified as potential sepsis biomarkers and therapeutic targets. Experimental studies have examined the biological mechanisms that might underpin the regulatory role of these ncRNAs in sepsis.

SUMMARY

Clinical applications of miRNAs and lncRNAs in sepsis are on the horizon. These data could lead to the identification of novel treatments or indeed support the repurposing of existing drugs for sepsis. Validation of the findings from these preliminary studies and crucially integration of multiomics datasets will undoubtedly revolutionize the clinical management of sepsis.

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.

Transforming Growth Factor-β and Long Non-coding RNA in Renal Inflammation and Fibrosis

Renal fibrosis is one of the most characterized pathological features in chronic kidney disease (CKD). Progressive fibrosis eventually leads to renal failure, leaving dialysis or allograft transplantation the only clinical option for CKD patients. Transforming growth factor-β (TGF-β) is the key mediator in renal fibrosis and is an essential regulator for renal inflammation. Therefore, the general blockade of the pro-fibrotic TGF-β may reduce fibrosis but may risk promoting renal inflammation and other side effects due to the diverse role of TGF-β in kidney diseases. Long non-coding RNAs (lncRNAs) are RNA transcripts with more than 200 nucleotides and have been regarded as promising therapeutic targets for many diseases. This review focuses on the importance of TGF-β and lncRNAs in renal inflammation, fibrogenesis, and the potential applications of TGF-β and lncRNAs as the therapeutic targets and biomarkers in renal fibrosis and CKD are highlighted.

Long Noncoding RNA: Regulatory Mechanisms and Therapeutic Potential in Sepsis

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection and is characterized by a hyperinflammatory state accompanied by immunosuppression. Long noncoding RNAs (lncRNAs) are noncoding RNAs longer than 200 nucleotides and have important roles in mediating various biological processes. Recently, lncRNAs were found to exert both promotive and inhibitory immune functions in sepsis, thus participating in sepsis regulation. Additionally, several studies have revealed that lncRNAs are involved in sepsis-induced organ dysfunctions, including cardiovascular dysfunction, acute lung injury, and acute kidney injury. Considering the lack of effective biomarkers for early identification and specific treatment for sepsis, lncRNAs may be promising biomarkers and even targets for sepsis therapies. This review systematically highlights the recent advances regarding the roles of lncRNAs in sepsis and sheds light on their use as potential biomarkers and treatment targets for sepsis.

Long Non-Coding RNA CASC2 Overexpression Ameliorates Sepsis-Associated Acute Kidney Injury by Regulating MiR-545-3p/PPARA Axis

BACKGROUND

Long non-coding RNAs (lncRNAs) have been demonstrated to be involved in the progression of sepsis-induced acute kidney injury (AKI). In this study, we aimed to explore the functions of lncRNA cancer susceptibility candidate 2 (CASC2) in sepsis-induced AKI.

METHODS

The sepsis cell models were established by exposing HK2 and HEK293 cells into lipopolysaccharide (LPS). Quantitative real-time polymerase chain reaction (qRT-PCR) assay was conducted to determine the expression of CASC2, miR-545-3p and peroxisome proliferator-activated receptor-α (PPARA) mRNA. Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis and wound healing assay were employed for cell viability, apoptosis and migration, respectively. Western blot assay was conducted for the protein levels of E-cadherin, α-SMA and PPARA. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by specific kits. The relationship between miR-545-3p and CASC2 or PPARA was verified by dual-luciferase reporter assay.

RESULTS

CASC2 level was decreased in sepsis patients' serums and LPS-treated HK2 and HEK293 cells. CASC2 overexpression facilitated cell viability and restrained cell apoptosis, migration, epithelial-mesenchymal transition (EMT) and oxidative stress in LPS-triggered HK2 and HEK293 cells. CASC2 was identified as a sponge for miR-545-3p to regulate PPARA expression. MiR-545-3p overexpression restored the impact of CASC2 on LPS-induced injury in HK2 and HEK293 cells. Moreover, miR-545-3p overexpression aggravated LPS-induced cell injury in HK2 and HEK293 cells by targeting PPARA.

CONCLUSION

CASC2 overexpression relieved the damage of HK2 and HEK293 cells mediated by LPS treatment through regulating miR-545-3p/PPARA axis.

MIR210HG Aggravates Sepsis-Induced Inflammatory Response of Proximal Tubular Epithelial Cell via the NF-κB Signaling Pathway

PURPOSE

Acute kidney injury (AKI) is a serious complication of sepsis and is characterized by inflammatory response. MicroRNA-210 host gene (MIR210HG) is upregulated in human proximal tubular epithelial cells under treatment of inflammatory cytokines. This study aimed to explore the role of MIR210HG in sepsis-induced AKI.

MATERIALS AND METHODS

Cell viability was detected by a cell counting kit 8 assay. The levels of proinflammatory cytokines were detected by enzyme-linked immunosorbent assay kits. The protein levels of p65, IκBα, and p-IκBα were examined by western blot analysis. The nuclear translocation of nuclear factor kappa B (NF-κB) was detected by immunofluorescence assay. The histological changes of kidneys were analyzed by hematoxylin and eosin staining assay.

RESULTS

Lipopolysaccharide (LPS) treatment significantly inhibited cell viability and increased productions of proinflammatory cytokines in proximal tubular epithelial cells (HKC-8). Additionally, MIR210HG levels in HKC-8 cells were increased by LPS treatment. MIR210HG silencing inhibited the LPS-induced cell inflammatory response. MIR210HG activated the NF-κB signaling pathway by promoting the phosphorylation of IκBα and nuclear translocation of p65. Rescue assays revealed that the MIR210HG-induced increase of cytokines levels and decline of cell viability were rescued by QNZ treatment. Knockdown of MIR210HG decreased blood urea nitrogen, serum creatinine, and proinflammatory cytokine levels in AKI rats. Moreover, the knockdown of MIR210HG protected against AKI-induced histological changes of kidneys in rats.

CONCLUSION

MIR210HG promotes sepsis-induced inflammatory response of HKC-8 cells by activating the NF-κB signaling pathway. This novel discovery may be helpful for the improvement of sepsis-induced AKI.

Long non-coding RNA NEAT1 promotes lipopolysaccharide-induced injury in human tubule epithelial cells by regulating miR-93-5p/TXNIP axis

Many long non-coding RNAs (lncRNAs) have been found to play crucial roles in sepsis-induced acute kidney injury (AKI), including lncRNA nuclear-enriched abundant transcript 1 (NEAT1). We aimed to further elucidate the functions and molecular mechanism of NEAT1 in sepsis-induced AKI. Sepsis-induced AKI cell model was established by treatment with lipopolysaccharide (LPS) in human tubule epithelial (HK2) cells. Cell viability and apoptosis were determined by Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. Western blot assay was performed to measure all protein levels. The concentrations of inflammatory factors were evaluated using enzyme-linked immunosorbent assay (ELISA). The expression levels of inflammatory factors, NEAT1, microRNA-93-5p (miR-93-5p), and thioredoxin-interacting protein (TXNIP) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The oxidative stress factors were detected using corresponding kits. The interaction between miR-93-5p and NEAT1 or TXNIP was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. NEAT1 was upregulated in serum of sepsis patients and LPS-induced HK2 cells. NEAT1 silence alleviated LPS-induced HK2 cell injury by inhibiting apoptosis, inflammation and oxidative stress. Moreover, miR-93-5p was a direct target of NEAT1, and suppression of NEAT1 weakened LPS-induced injury by upregulating miR-93-5p in HK2 cells. Furthermore, TXNIP was a downstream target of miR-93-5p, and miR-93-5p attenuated LPS-induced HK2 cell injury by downregulating TXNIP. In addition, NEAT1 regulated TXNIP expression by acting as a sponge of miR-93-5p. NEAT1 might aggravate LPS-induced injury in HK2 cells by regulating miR-93-5p/TXNIP axis, providing a potential therapeutic strategy for sepsis-associated AKI.

Down-Regulation of miR-181a-5p Prevents Cerebral Ischemic Injury by Upregulating En2 and Activating Wnt/β-catenin Pathway

PURPOSE

Cerebral ischemic injury contributes to severe dysfunction of the brain, which triggers extremely high mortality and disability. The role of microRNA (miR)-181a-5p is documented in cerebral ischemic injury. Therefore, this study intended to further figure out the mechanism of miR-181a-5p in cerebral ischemic injury.

METHODS

miR-181a-5p expression in middle cerebral artery occlusion (MCAO) mouse model, oxygen-glucose-deprivation/reoxygenation (OGD/R) N2a cell model, and serum from acute ischemic injury (ACI) patients was evaluated using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Gain- and loss-of-function assays were implemented in MCAO mice and OGD/R-induced N2a cells. In mice, the cerebral infarction area was assessed with 2,3,5-triphenyltetrazolium chloride staining, the number of damaged neurons by Nissl staining, and apoptosis by TdT-mediated dUTP-biotin nick end-labeling staining. Moreover, N2a cell apoptosis and proliferation were determined with flow cytometry or 5-ethynyl-2'-deoxyuridine staining, respectively. The expression of En2 and Wnt/β-catenin pathway-related factors was determined with RT-qPCR and Western blot analysis. The targeting relationship between miR-181a-5p and En2 was evaluated by dual luciferase reporter gene assay.

RESULTS

miR-181a-5p was highly expressed in serum of ACI patients, MCAO mice, and OGD/R-induced N2a cells. En2, lowly expressed in MCAO mice, was targeted by miR-181a-5p, and miR-181a-5p down-regulation activated the Wnt/β-catenin pathway. Furthermore, miR-181a-5p inhibition or En2 overexpression reduced cerebral infarction area, the number of damaged neurons, and apoptosis in MCAO mice, and also diminished apoptosis and accelerated proliferation of OGD/R-induced N2a cells.

CONCLUSION

miR-181a-5p suppression activated Wnt/β-catenin pathway and sequentially attenuated cerebral ischemic injury by targeting En2.

Identification of the candidate lncRNA biomarkers for acute kidney injury: a systematic review and meta-analysis

Background: This meta-analysis aims to summarize the studies of lncRNAs dysregulation in individual acute kidney injury (AKI) and identify the potential lncRNA biomarkers of AKI.Research design and methods: We systematically searched four databases to identify the lncRNA expression studies of AKI in animal models and patients. The lncRNAs expression data were extracted from 38 included studies, and lncRNA vote-counting strategy was applied to identify significant lncRNA biomarkers. The predicted targets of lncRNA biomarkers were obtained by searching Co-LncRNA, RBPmap, and LncBase v.2. Further, GO enrichment analysis and KEGG pathway analysis were performed.Results: We recognized a significant lncRNA signature of 21 up-regulated and 11 down-regulated lncRNAs, among which TapSAKI, XIST, MALAT1, CASC2, and HOXA-AS2 were dysregulated both in AKI rodent models and patients. About 28.0% of these lncRNAs mainly exist in the nucleus, which was also the most enriched GO cellular components term. The most relevant GO terms in biological process and molecular function associated with these lncRNAs were splicing, processing, and binding of mRNA.Conclusions: The present meta-analysis identified 31 significant dysregulated lncRNAs from 38 studies. TapSAKI, XIST, MALAT1, CASC2, and HOXA-AS2 were considered as the potential predictive biomarkers and therapeutic targets of AKI.

The role of peroxisome proliferator-activated receptors (PPAR) in immune responses

Peroxisome proliferator-activated receptors (PPARs) are fatty acid-activated transcription factors of nuclear hormone receptor superfamily that regulate energy metabolism. Currently, three PPAR subtypes have been identified: PPARα, PPARγ, and PPARβ/δ. PPARα and PPARδ are highly expressed in oxidative tissues and regulate genes involved in substrate delivery and oxidative phosphorylation (OXPHOS) and regulation of energy homeostasis. In contrast, PPARγ is more important in lipogenesis and lipid synthesis, with highest expression levels in white adipose tissue (WAT). In addition to tissues regulating whole body energy homeostasis, PPARs are expressed in immune cells and have an emerging critical role in immune cell differentiation and fate commitment. In this review, we discuss the actions of PPARs in the function of the innate and the adaptive immune system and their implications in immune-mediated inflammatory conditions.

RETRACTED: Protective role of long noncoding RNA CRNDE in myocardial tissues from injury caused by sepsis through the microRNA-29a/SIRT1 axis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of Editor-in-Chief and the corresponding author. The corresponding author confessed that the paper was outsourced to a third-party company, who could not guarantee the integrity of the data.

Exosomes in Nephropathies: A Rich Source of Novel Biomarkers

The biomarkers commonly utilized in diagnostic evaluations of kidney disease suffer from low sensitivity, especially in the early stages of renal damage. On the other hand, obtaining a renal biopsy to augment clinical decision making can lead to potentially serious complications. In order to overcome the shortcomings of currently available diagnostic tools, recent studies suggest that exosomes, cell-secreted extracellular vesicles containing a large array of active molecules to facilitate cell-to-cell communication, may represent a rich source of novel disease biomarkers. Because of their endocytic origin, exosomes carry markers typical for their parent cells, which could permit the localization of biochemical cellular alterations in specific kidney compartments. Different types of exosomes can be isolated from noninvasively obtained biofluids; however, in the context of kidney disease, evidence has emerged on the role of urinary exosomes in the diagnostic and predictive modeling of renal pathology. The current review summarizes the potential application of exosomes in the detection of acute and chronic inflammatory, metabolic, degenerative, and genetic renal diseases.

Effects and Mechanism of lncRNA CRNDE on Sepsis-Induced Acute Kidney Injury

Objective

To investigate the effects of lncRNA CRNDE on sepsis-associated acute kidney injury in the human kidney 2 cell line and explore the potential mechanisms.

Methods

HK-2 cells were treated with lipopolysaccharides to induce injuries. The expression of CRNDE and miR-146a in HK-2 cells were altered by a transient transfection assay. Cell apoptosis was detected by a flow cytometry assay, and the levels of inflammatory cytokines including TNF-α, IL-6, IL-8, and IL-1β were assessed by ELISA. Furthermore, western blot analysis was performed to detect the expression levels of TLR4/NF-κB pathway-related proteins. And a luciferase reporter gene assay was used to verify if miR-146a was the target of CRNDE.

Results

LPS treatment increased CRNDE expression in HK-2 cells. CRNDE overexpression enhanced cell injuries in HK-2 cells significantly increasing inflammatory cytokine levels, including TNF-α, IL-6, IL-8, and IL-1β, and cell apoptosis. In addition, CRNDE overexpression further activated the TLR4/NF-κB pathways in HK-2 cells. Inversely, opposite results were observed in the miR-146a mimic treatment group, and the miR-146a inhibitor could reverse the protein expression changes of TLR4/NF-κB in the si-CRNDE and LPS treatment group.

Conclusion

This study demonstrated that CRNDE overexpression could activate the TLR4/NF-κB signaling pathway by regulating miR-146a, which accelerated LPS-induced inflammation and apoptosis in HK-2 cells.

Novel lncRNA XLOC_032768 alleviates cisplatin-induced apoptosis and inflammatory response of renal tubular epithelial cells through TNF-α

The cellular and molecular mechanisms through which cisplatin induces nephrotoxicity have been investigated extensively. However, the role of long non-coding RNAs (lncRNAs) in cisplatin-induced nephrotoxicity is not well known. We explored the functions and underlying mechanisms of a novel lncRNA XLOC_032768 in cisplatin-induced nephrotoxicity. Cisplatin treatment resulted in the apoptosis of the renal tubular epithelial cells and inflammatory response in a mouse model and human renal proximal tubular epithelial cells (HK-2). The differentially expressed genes (DEGs) of the transcriptome data were determined, and the results showed that lncRNA XLOC_032768 expression was significantly repressed by cisplatin treatment. This result was validated by an RT-qPCR experiment on in vivo and in vitro models. The overexpression of XLOC_032768 significantly inhibited the cisplatin-induced apoptosis and inflammatory response in HK-2 cells and mouse exposed to cisplatin. RNA sequencing analysis further confirmed that XLOC_032768 could regulate tumor necrosis factor (TNF)-α in the cisplatin-induced apoptosis of HK-2 cells in trans-manner. TNF-α inhibition also ameliorated cisplatin-induced apoptosis of renal tubular epithelial cells and renal structural damage. As such, XLOC_032768 suppressed cisplatin-induced apoptosis and inflammatory response of renal tubular epithelial cells through TNF-α. LncRNA XLOC_032768 is a potential novel agent to reduce cisplatin-induced nephrotoxicity.

miR-21 protects against lipopolysaccharide-stimulated acute kidney injury and apoptosis by targeting CDK6

Background

Septic acute kidney injury (AKI) causes a sharp deterioration of renal function, and it is a major reason for mortality in intensive care units. Although miR-21 has been proven to be dysregulated in patients with sepsis, the evidence is scarce concerning its role in mediating cellular apoptosis in AKI.

Methods

Mice were injected intraperitoneally with 10 mg/kg of lipopolysaccharide (LPS) to establish septic AKI model, miR-21 mimic and inhibitor were used to manipulate the expression of miR-21, the creatinine levels were detected by a creatinine assay kit, the renal cell proliferation and apoptosis were detected by MTT assay, flow cytometry assay and acridine orange/ethidium bromide (AO/EB) fluorescence staining, the renal function was evaluated by renal histology and tubular injury score, western blot analysis was used to detect the target protein levels. Several bioinformatics tools were performed to show the downstream target of miR-21, and further confirmed by luciferase reporter assay and caspase-3 activity assay.

Results

miR-21 silencing was able to promote renal function and decrease LPS-stimulated renal cell apoptosis in vitro and in vivo, and it could decrease the Bax/Bcl-2 ratio and caspase-3 activity. On the contrary, miR-21 overexpression had the opposite effects. Cyclin-dependent kinase 6 (CDK6) was confirmed as a target gene of miR-21 and was associated with renal cell apoptosis. Moreover, miR-21 was also found to be up-regulated in septic AKI.

Conclusions

Current evidences suggest that miR-21 has a potential application in treating septic AKI.