The role of regulatory T cells in the pathogenesis of acute kidney injury

The incidence of acute kidney injury (AKI) is on the rise and is associated with high mortality; however, there are currently few effective treatments. Moreover, the relationship between Tregs and other components of the immune microenvironment (IME) in the pathogenesis of AKI remains unclear. We downloaded four publicly accessible AKI datasets, GSE61739, GSE67401, GSE19130, GSE81741, GSE19288 and GSE106993 from the gene expression omnibus (GEO) database. Additionally, we gathered two kidney single-cell sequencing (scRNA-seq) samples from the Department of Organ Transplantation at Zhujiang Hospital of Southern Medical University to investigate chronic kidney transplant rejection (CKTR). Moreover, we also collected three samples of normal kidney tissue from GSE131685. By analysing the differences in immune cells between the AKI and Non-AKI groups, we discovered that the Non-AKI group contained a significantly greater number of Tregs than the AKI group. Additionally, the activation of signalling pathways, such as inflammatory molecules secretion, immune response, glycolytic metabolism, NOTCH, FGF, NF-κB and TLR4, was significantly greater in the AKI group than in the Non-AKI group. Additionally, analysis of single-cell sequencing data revealed that Tregs in patients with chronic kidney rejection and in normal kidney tissue have distinct biology, including immune activation, cytokine production, and activation fractions of signalling pathways such as NOTCH and TLR4. In this study, we found significant differences in the IME between AKI and Non-AKI, including differences in Tregs cells and activation levels of biologically significant signalling pathways. Tregs were associated with lower activity of signalling pathways such as inflammatory response, inflammatory molecule secretion, immune activation, glycolysis.     

Noncoding RNAs in acute kidney injury

Acute kidney injury (AKI), caused by various stimuli including ischemia reperfusion, nephrotoxic insult, and sepsis, is characterized by abrupt decline of kidney function. Till now, the molecular mechanisms for AKI have not been fully explored and the effective therapies are still lacking. Noncoding RNAs (ncRNAs), a group of biomolecules function at RNA level, are involved in a wide range of physiopathological processes including AKI. MicroRNAs (miRNAs) are the most extensively studied ncRNAs in AKI. Evidence indicated that miRNAs are altered significantly in various types of AKI. Gain-and-loss-of-function studies demonstrated that miRNAs, such as miR-24, miR-126, miR-494, and miR-687, may bind to the 3′-untranslated region of their target genes to regulate inflammation, programmed cell death, and cell cycle in the injury and repair stages of AKI, indicating their therapeutic potential in AKI. In contrast, functions of long noncoding RNAs and circular RNAs in AKI are hot topics but still largely unknown. Additionally, ncRNAs packaged in exosome can be detected in circulation and urine, they may serve as specific biomarkers for AKI. This review summarized the alteration and functional role of ncRNAs and their therapeutic potential in AKI.     

microRNA－21在肿瘤中异常表达的意义

microRNA（miRNA）是由18～26个核苷酸组成的内源性非编码的单链RNA分子,其通过与mRNA的结合来抑制其翻译过程从而调节相应基因的表达,在人体一系列生物学过程发挥着作用。miR-21在众多肿瘤组织中表达上调,临床试验证实miR-21的表达水平与肿瘤的临床分期,转移,预后存在密切联系,因此miR－21成为了癌症基因治疗的新靶点。     

Role of endoplasmic reticulum stress and autophagy in the transition from acute kidney injury to chronic kidney disease

Acute kidney injury (AKI) and chronic kidney disease (CKD) are global health concerns with increasing rates in morbidity and mortality. Transition from AKI-to-CKD is common and requires awareness in the management of AKI survivors. AKI-to-CKD transition is a main risk factor for the development of cardiovascular disease and progression to end-stage kidney disease. The mechanisms driving AKI-to-CKD transition are being explored to identify potential molecular and cellular targets for renoprotective drug interventions. Endoplasmic reticulum (ER) stress and autophagy are involved in the process of AKI-to-CKD transition. Excessive ER stress results in the persistent activation of unfolded protein response, which is an underneath cause of kidney cell death. Moreover, ER stress modulates autophagy and vice-versa. Autophagy is a degradation defensive mechanism protecting cells from malfunction. However, the underlying pathological mechanism involved in this interplay in the context of AKI-to-CKD transition is still unclear. In this review, we discuss the crosstalk between ER stress and autophagy in AKI, AKI-to-CKD transition, and CKD progression. In addition, we explore possible therapeutic targets that can regulate ER stress and autophagy to prevent AKI-to-CKD transition to improve the long-term prognosis of AKI survivors.     

炎症与急性缺血性肾损伤

近年来研究发现细胞间黏附分子-1和单核细胞趋化蛋白-1等炎症因子、核因子-κB及中性粒细胞、单核/巨噬细胞等炎症细胞参与了急性缺血性肾损伤的发生发展,抑制急性缺血性肾损伤时肾脏的炎症反应具有保护肾脏作用.     

Lansoprazole promotes cisplatin-induced acute kidney injury via enhancing tubular necroptosis

Acute kidney injury (AKI) is the main obstacle that limits the use of cisplatin in cancer treatment. Proton pump inhibitors (PPIs), the most commonly used class of medications for gastrointestinal complications in cancer patients, have been reported to cause adverse renal events. However, the effect of PPIs on cisplatin-induced AKI remains unclear. Herein, the effect and mechanism of lansoprazole (LPZ), one of the most frequently prescribed PPIs, on cisplatin-induced AKI were investigated in vivo and in vitro. C57BL/6 mice received a single intraperitoneal (i.p.) injection of cisplatin (18 mg/kg) to induce AKI, and LPZ (12.5 or 25 mg/kg) was administered 2 hours prior to cisplatin administration and then once daily for another 2 days via i.p. injection. The results showed that LPZ significantly aggravated the tubular damage and further increased the elevated levels of serum creatinine and blood urea nitrogen induced by cisplatin. However, LPZ did not enhance cisplatin-induced tubular apoptosis, as evidenced by a lack of significant change in mRNA and protein expression of Bax/Bcl-2 ratio and TUNEL staining. Notably, LPZ increased the number of necrotic renal tubular cells compared to that by cisplatin treatment alone, which was further confirmed by the elevated necroptosis-associated protein expression of RIPK1, p-RIPK3 and p-MLKL. Furthermore, LPZ deteriorated cisplatin-induced inflammation, as revealed by the increased mRNA expression of pro-inflammatory factors including, NLRP3, IL-1β, TNF-α and caspase 1, as well as neutrophil infiltration. Consistently, in in vitro study, LPZ increased HK-2 cell death and enhanced inflammation, compared with cisplatin treatment alone. Collectively, our results demonstrate that LPZ aggravates cisplatin-induced AKI, and necroptosis may be involved in the exacerbation of kidney damage.     

Sirtuin 6 overexpression relieves sepsis-induced acute kidney injury by promoting autophagy

Sirtuin 6 (SIRT6) has the function of regulating autophagy. The aim of this study was to investigate the mechanism through which SIRT6 relieved acute kidney injury (AKI) caused by sepsis. The AKI model was established with lipopolysaccharides (LPS) using mice. Hematoxylin-eosin (HE) staining and streptavidin-perosidase (SP) staining was used to observe kidney tissue and test SIRT6 and LC3B proteins in kidney. Enzyme-linked immunosorbent assay (ELISA) was performed to detected the tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) concentrations. Cell counting kit-8 (CCK-8) assay and flow cytometry were carried out to test the cell viability and apoptosis rate respectively. Protein and mRNA were determined by Western blot and quantitative real-time polymerase chain reaction (qRT-PCR). AKI induced by LPS had self-repairing ability. At 12 h after modeling, the expression levels of TNF-α, IL-6, SIRT6 and LC3B-II/LC3B-I were first significantly increased and were then significantly decreased at 48 h after modeling. LPS inhibited the growth of HK-2 cells and promoted the expressions of TNF-α, IL-6, SIRT6 and LC3B. Overexpression of SIRT6 down-regulated the secretion of TNF-α and IL-6 induced by LPS. SIRT6 overexpression inhibited apoptosis induced by LPS and promoted autophagy in HK-2 cells. Silencing of the SIRT6 gene not only promoted the secretion of TNF-α and IL-6 by HK-2 cells, but also promoted apoptosis and reduced autophagy. LPS up-regulated the expression of SIRT6 gene in HK-2 cells. Overexpression of the SIRT6 gene could inhibit apoptosis and induce autophagy, which might be involved in repairing kidney damage caused by LPS.     

The yin and yang of autophagy in acute kidney injury

Antagonizing the strongly activated pathway of autophagy in renal ischemic injury has been associated with poor outcome. In our recent study we used mice with a selective deletion of Atg5 in the S3 proximal tubule segment, which is most susceptible to ischemic damage. In line with the notion that autophagy is a prosurvival mechanism our studies revealed an early accelerated cell death of heavily damaged tubular cells in the S3 segment of these mice. Interestingly, this expedited loss of cells was associated with better long-term outcome as reflected by less inflammation, improved tubular repair, and function and reduced accumulation of senescent cells. While these data confirm the role of tubular autophagy as a prosurvival mechanism in ischemic kidney injury, they also show that autophagy may enable severely damaged cells to persist and exert deleterious effects. Such ambivalent effects might be of relevance if modulating autophagy is considered as a therapeutic option.     

Renoprotective mechanisms of Astragaloside IV in cisplatin-induced acute kidney injury

Nephrotoxicity remains a serious adverse effect of cisplatin chemotherapy, limiting its clinical usage. Numerous studies show that oxidative stress and inflammation are closely associated with cisplatin-induced renal damage. Astragaloside IV (AS-IV) has been found to possess antioxidant and anti-inflammation functions. Therefore, we investigated the potential curative effects of AS-IV against cisplatin-induced renal injury and the possible cellular mechanism for activity, both in vitro and in vivo. We found that pretreatment of HK-2 cells with AS-IV could mitigate cisplatin-induced cell damage caused by oxygen-free radicals and the inflammatory response, as evidenced by reduced formation of reactive oxygen species (ROS) and inflammatory cytokines. AS-IV improved cisplatin-induced renal dysfunction and histopathological injury in mice. Additionally, AS-IV enhanced the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT). It also inhibited cisplatin-induced overproduction of kidney injury molecule-1 (KIM-1), malondialdehyde (MDA), tumour necrosis factor-α (TNF???α), and interleukin-1β (IL-1β) in kidney tissues. We found that the protective effects of AS-IV occurred via activation of the nuclear factor-erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) proteins and inhibition of nuclear factor-κappaB (NF-κB) activation. Further, small interfering RNA (siRNA) knockdown of Nrf2 abrogated the protective effects of AS-IV against cisplatin-induced oxidative stress and blocked the inhibitory effects of AS-IV on cisplatin-induced NF-κB activation and inflammatory cytokine production. In conclusion, our data suggested that AS-IV attenuated cisplatin-mediated renal injury, and these protective effects might be due to inhibition of both oxidative damage and inflammatory response via activation of Nrf2 system and suppression of NF-κB activation.     

Cellular senescence,a novel therapeutic target for mesenchymal stem cells in acute kidney injury

Cellular senescence is a widespread cellular programme that is characterized by permanent cell cycle arrest. Senescent cells adopt a changed secretory phenotype that can alter cellular function. For years, cellular senescence has been thought to be a protective factor against cancer; however, it is now recognized that it has a dual effect on individuals. Co-ordinated activation of cellular senescence provides advantages during embryogenesis, wound healing, tissue repair and inhibition of tumorigenesis. On the other hand, the aberrant generation and accumulation of abnormal senescent cells lead to the development of age-related conditions and tissue deterioration. During acute kidney injury (AKI), the kidney faces multiple types of stressors and challenges, which can easily drive cellular senescence. How to appropriately progress through the cell cycle and minimize long-term damage is of great importance to the acquisition of adaptive repair considering that no available therapeutic interventions can reliably limit injury, speedy recovery or improve the prognosis of this syndrome. Whether the manipulation of cellular senescence can become a novel therapeutic target in AKI and reignite clinical and research interest remains to be determined. Here, we share our current understanding of the role of cellular senescence in AKI, along with examples of the application of mesenchymal stem cells (MSCs) for targeting this disorder during its treatment.     

Adenovirus-mediated interleukin-13 gene therapy attenuates acute kidney allograft injury

BACKGROUND: Kidney transplantation is possible by virtue of systemic immunosuppression, which is in turn accompanied by serious side effects. The search for novel therapeutic agents and strategies is ongoing. Here we investigate the effects of adenovirus-mediated gene therapy with interleukin (IL)-13, which is a cytokine with strong immunomodulatory properties, on acute renal allograft injury. In addition, we compare the effects of local (intrarenal) and systemic (intramuscular) IL-13 gene therapy in kidney transplantation. METHODS: The experiments were performed in a rat Fisher to Lewis acute rejection model of kidney transplantation. An adenovirus-IL-13 or adenovirus-luciferase was injected either into the donor kidney before transplantation (local treatment) or into the hind leg muscle of recipient rats (systemic treatment). A group with no treatment served as control. No additional immunosuppressive therapy was applied. The rats were sacrificed after 8 days and inflammatory markers and renal pre-fibrosis were assessed. RESULTS: Efficient gene transfer was confirmed by ELISA, immunohistochemistry and real-time PCR. IL-13 gene therapy diminished graft infiltration with macrophages and cytotoxic T cells and limited up-regulation of mRNA levels of the adhesion molecule E-selectin and pro-inflammatory cytokines TNF-alpha and IFN-gamma. Moreover, reduced renal interstitial pre-fibrosis was found in the rats receiving IL-13 gene therapy. The effects of local and systemic therapy were similar. CONCLUSIONS: This study demonstrates that IL-13 gene therapy in the graft significantly attenuates acute renal allograft damage, suggesting local therapy with IL-13 as a strategy to reduce the need for systemic immunosuppressive medication and thereby its side effects.     

MicroRNA-21在卵巢癌病灶转移过程中的作用及机制研究

目的:探讨micro RNA-21在卵巢癌病灶转移过程中的作用及其机制。方法:选取本院2016年6月-2018年5月收治的138例卵巢癌患者,其中63例出现结直肠转移,75例未发现有转移。q RT-PCR分别检测两组患者肿瘤组织、癌旁组织和正常组织中micro RNA-21的表达;Western blot检测两组患者肿瘤组织中PGDH、PGE2、Twist表达。通过转染过表达载has-micro RNA-21上调A2780细胞中micro RNA-21的表达,采用平板克隆实验检测细胞克隆形成能力,Trans-well细胞迁移实验和侵袭实验分别检测细胞迁移和侵袭能力。Western blot检测PGDH、PGE2、Twist蛋白表达。结果:卵巢癌转移组肿瘤组织中micro RNA-21表达高于未转移组、癌旁组织和正常卵巢组织(P0.05),卵巢癌转移组肿瘤组织中PGDH表达低于未转移组,而PGE2、Twist表达高于未转移组(P0.05)。micro RNA-21过表达的A2780细胞平板克隆形成能力、迁移和侵袭能力及上皮间质转化相关蛋白PGE2和Twist表达均明显高于阴性对照组(P0.05),而PGDH表达的表达明显降低(P0.05)。结论:micro RNA-21可能通过抑制PGDH的表达增加PGE2的表达,进而激活上皮间质转化,促进卵巢癌转移。     

Importance of glycosylation in the interaction of Tamm-Horsfall protein with collectin-11 and acute kidney injury

Both Tamm-Horsfall protein (THP) and collectin-11 (CL-11) are important molecules in acute kidney injury (AKI). In this study, we measured the change of glycosylation of THP in patients with AKI after surgery, using MALDI-TOF MS and lectin array analysis. The amount of high-mannose and core fucosylation in patients with AKI were higher than those in healthy controls. In vitro study showed that THP could bind to CL-11 with affinity at 9.41 × 10⁻⁷ mol/L and inhibited activation of complement lectin pathway. The binding affinity decreased after removal of glycans on THP. Removal of fucose completely ablated the binding between the two proteins. While removal of high-mannose or part of the N-glycan decreased the binding ability to 30% or 60%. The results indicated that increase of fucose on THP played an important role via complement lectin pathway in AKI.     

HO-1 mitigates acute kidney injury and subsequent kidney-lung cross-talk

Abstract

Ischemia-reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI), which contributes to the development of chronic kidney disease (CKD). IRI-induced AKI releases proinflammatory cytokines (e.g. IL-1β, TNF-α, IL-6) that induce a systemic inflammatory response, resulting in proinflammatory cells recruitment and remote organ damage. AKI is associated with poor outcomes, particularly when extrarenal complications or distant organ injuries occur. Acute lung injury (ALI) is a major remote organ dysfunction associated with AKI. Hence, kidney-lung cross-talk remains a clinical challenge, especially in critically ill population. The stress-responsive enzyme, heme oxygenase-1 (HO-1) is largely known to protect against renal IRI and may be preventively induced using hemin prior to renal insult. However, the use of hemin-induced HO-1 to prevent AKI-induced ALI remains poorly investigated. Mice received an intraperitoneal injection of hemin or sterile saline 1?day prior to surgery. Twenty-four hours later, mice underwent bilateral renal IRI for 26?min or sham surgery. After 4 or 24?h of reperfusion, mice were sacrificed. Hemin-induced HO-1 improved renal outcomes after IRI (i.e. fewer renal damage, renal inflammation, and oxidative stress). This protective effect was associated with a dampened systemic inflammation (i.e. IL-6 and KC). Subsequently, mitigated lung inflammation was found in hemin-treated mice (i.e. neutrophils influx and lung KC). The present study demonstrates that hemin-induced HO-1 controls the magnitude of renal IRI and the subsequent AKI-induced ALI. Therefore, targeting HO-1 represents a promising approach to prevent the impact of renal IRI on distant organs, such as lung.     

Novel biomarkers for post-contrast acute kidney injury identified from long non-coding RNA expression profiles

Background: Post-contrast acute kidney injury (PC-AKI) is a severe complication of cardiac catheterization. Emerging evidence indicated that long non-coding RNAs (lncRNAs) could serve as biomarkers for various diseases. However, the lncRNA expression profile and potential biomarkers in PC-AKI remain unclear. This study aimed to investigate novel lncRNA biomarkers for the early detection of PC-AKI.Methods: lncRNA profile in the kidney tissues of PC-AKI rats was evaluated through RNA sequencing. Potential lncRNA biomarkers were identified through human-rat homology analysis, kidney and blood filtering in rats and verified in 112 clinical samples. The expression patterns of the candidate lncRNAs were detected in HK-2 cells and rat models to evaluate their potential for early detection.Results: In total, 357 lncRNAs were found to be differentially expressed in PC-AKI. We identified lnc-HILPDA and lnc-PRND were conservative and remarkably upregulated in both kidneys and blood from rats and the blood of PC-AKI patients; these lncRNAs can precisely distinguish PC-AKI patients (area under the curve (AUC) values of 0.885 and 0.875, respectively). The combination of these two lncRNAs exhibited improved accuracy for predicting PC-AKI, with 100% sensitivity and 83.93% specificity. Time-course experiments showed that the significant difference was first noted in the blood of PC-AKI rats at 12 h for lnc-HILPDA and 24 h for lnc-PRND.Conclusion: Our study revealed that lnc-HILPDA and lnc-PRND may serve as the novel biomarkers for early detection and profoundly affect the clinical stratification and strategy guidance of PC-AKI.