BACKGROUND: Ischemic acute kidney injury (AKI) is a common syndrome associated with considerable mortality and healthcare costs. Up to now, the underlying pathogenesis of ischemic AKI remains incompletely understood, and specific strategies for early diagnosis and treatment of ischemic AKI are still lacking. Here, this study aimed to define the transcriptomic landscape of AKI patients through single-cell RNA sequencing (scRNA-seq) analysis in kidneys. METHODS: In this study, scRNA-seq technology was applied to kidneys from two ischemic AKI patients, and three human public scRNA-seq datasets were collected as controls. Differentially expressed genes (DEGs) and cell clusters of kidneys were determined. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, as well as the ligand-receptor interaction between cells, were performed. We also validated several DEGs expression in kidneys from human ischemic AKI and ischemia/reperfusion (I/R) injury induced AKI mice through immunohistochemistry staining. RESULTS: 15 distinct cell clusters were determined in kidney from subjects of ischemic AKI and control. The injured proximal tubules (PT) displayed a proapoptotic and proinflammatory phenotype. PT cells of ischemic AKI had up-regulation of novel pro-apoptotic genes including USP47 , RASSF4 , EBAG9 , IER3 , SASH1 , SEPTIN7 , and NUB1 , which have not been reported in ischemic AKI previously. Several hub genes were validated in kidneys from human AKI and renal I/R injury mice, respectively. Furthermore, PT highly expressed DEGs enriched in endoplasmic reticulum stress, autophagy, and retinoic acid-inducible gene I (RIG-I) signaling. DEGs overexpressed in other tubular cells were primarily enriched in nucleotide-binding and oligomerization domain (NOD)-like receptor signaling, estrogen signaling, interleukin (IL)-12 signaling, and IL-17 signaling. Overexpressed genes in kidney-resident immune cells including macrophages, natural killer T (NKT) cells, monocytes, and dendritic cells were associated with leukocyte activation, chemotaxis, cell adhesion, and complement activation. In addition, the ligand-receptor interactions analysis revealed prominent communications between macrophages and monocytes with other cells in the process of ischemic AKI. CONCLUSION Together, this study reveals distinct cell-specific transcriptomic atlas of kidney in ischemic AKI patients, altered signaling pathways, and potential cell-cell crosstalk in the development of AKI. These data reveal new insights into the pathogenesis and potential therapeutic strategies in ischemic AKI.
Humans ; Mice ; Animals ; Transcriptome/genetics* ; Ligands ; Kidney/metabolism* ; Acute Kidney Injury/metabolism* ; Ischemia/metabolism* ; Reperfusion Injury/metabolism* ; Sequence Analysis, RNA ; Adaptor Proteins, Signal Transducing/metabolism* ; Tumor Suppressor Proteins/metabolism*

Sepsis-induced uncontrolled systemic inflammatory response syndrome (SIRS) is a critical cause of multiple organ failure. Acute kidney injury (AKI) is one of the most serious complications associated with an extremely high mortality rate in SIRS, and it lacked simple, safe, and effective treatment strategies. Leontopodium leontopodioides (Willd.) Beauv (LLB) is commonly used in traditional Chinese medicine for the treatment of acute and chronic nephritis. However, it remains unclear whether lipopolysaccharide (LPS) affects LPS-induced AKI. To identify the molecular mechanisms of LLB in LPS-induced HK-2 cells and mice, LLB was prepared by extraction with 70% methanol, while a lipopolysaccharide (LPS)-induced HK-2 cell model and an AKI model were established in this study. Renal histopathology staining was performed to observe the morphology changes. The cell supernatant and kidney tissues were collected for determining the levels of inflammatory factors and protein expression by ELISA, immunofluorescence, and Western blot. The results indicated that LLB significantly reduced the expression of IL-6 and TNF-α in LPS-induced HK-2 cells, as well as the secretion of IL-6, TNF-α, and IL-1β in the supernatant. The same results were observed in LPS-induced AKI serum. Further studies revealed that LLB remarkably improved oxidative stress and apoptosis based on the content of MDA, SOD, and CAT in serum and TUNEL staining results. Notably, LLB significantly reduced the mortality due to LPS infection. Renal histopathology staining results supported these results. Furthermore, immunofluorescence and Western blot results confirmed that LLB significantly reduced the expression of the protein related to the NF-κB signaling pathway and NLRP3, ASC, and Caspase-1 which were significantly increased through LPS stimulation. These findings clearly demonstrated the potential use of LLB in the treatment of AKI and the crucial role of the NF-κB/NLRP3 pathway in the process through which LLB attenuates AKI induced by LPS.
Animals ; Mice ; NF-kappa B/metabolism* ; Lipopolysaccharides/adverse effects* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Interleukin-6/metabolism* ; Acute Kidney Injury/metabolism* ; Kidney ; Systemic Inflammatory Response Syndrome/pathology*

The present study was aimed to investigate whether Gasdermin D (GSDMD)-mediated pyroptosis participated in lipopolysaccharide (LPS)-induced sepsis-associated acute kidney injury (AKI), and to explore the role of caspase-1 and caspase-11 pyroptosis pathways in this process. The mice were divided into four groups: wild type (WT), WT-LPS, GSDMD knockout (KO) and KO-LPS. The sepsis-associated AKI was induced by intraperitoneal injection of LPS (40 mg/kg). Blood samples were taken to determine the concentration of creatinine and urea nitrogen. The pathological changes of renal tissue were observed via HE staining. Western blot was used to investigate the expression of pyroptosis-associated proteins. The results showed that the concentrations of serum creatinine and urea nitrogen in the WT-LPS group were significantly increased, compared with those in the WT group (P < 0.01); whereas serum creatinine and urea nitrogen in the KO-LPS group were significantly decreased, compared with those in the WT-LPS group (P < 0.01). HE staining results showed that LPS-induced renal tubular dilatation was mitigated in GSDMD KO mice. Western blot results showed that LPS up-regulated the protein expression levels of interleukin-1β (IL-1β), GSDMD and GSDMD-N in WT mice. GSDMD KO significantly down-regulated the protein levels of IL-1β, caspase-11, pro-caspase-1, caspase-1(p22) induced by LPS. These results suggest that GSDMD-mediated pyroptosis is involved in LPS-induced sepsis-associated AKI. Caspase-1 and caspase-11 may be involved in GSDMD cleavage.
Animals ; Mice ; Acute Kidney Injury ; Caspase 1 ; Caspases/metabolism* ; Creatinine ; Lipopolysaccharides ; Mice, Knockout ; Nitrogen ; Sepsis ; Urea ; Gasdermins/metabolism*

OBJECTIVE: To investigate protective effect of Cordyceps sinensis (CS) through autophagy-associated adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway in acute kidney injury (AKI)-induced acute lung injury (ALI). METHODS: Forty-eight male Sprague-Dawley rats were divided into 4 groups according to a random number table, including the normal saline (NS)-treated sham group (sham group), NS-treated ischemia reperfusion injury (IRI) group (IRI group), and low- (5 g/kg·d) and high-dose (10 g/kg·d) CS-treated IRI groups (CS1 and CS2 groups), 12 rats in each group. Nephrectomy of the right kidney was performed on the IRI rat model that was subjected to 60 min of left renal pedicle occlusion followed by 12, 24, 48, and 72 h of reperfusion. The wet-to-dry (W/D) ratio of lung, levels of serum creatinine (Scr), blood urea nitrogen (BUN), inflammatory cytokines such as interleukin- β and tumor necrosis factor- α, and biomarkers of oxidative stress such as superoxide dismutase, malonaldehyde (MDA) and myeloperoxidase (MPO), were assayed. Histological examinations were conducted to determine damage of tissues in the kidney and lung. The protein expressions of light chain 3 II/light chain 3 I (LC3-II/LC3-I), uncoordinated-51-like kinase 1 (ULK1), P62, AMPK and mTOR were measured by Western blot and immunohistochemistry, respectively. RESULTS: The renal IRI induced pulmonary injury following AKI, resulting in significant increases in W/D ratio of lung, and the levels of Scr, BUN, inflammatory cytokines, MDA and MPO (P<0.01); all of these were reduced in the CS groups (P<0.05 or P<0.01). Compared with the IRI groups, the expression levels of P62 and mTOR were significantly lower (P<0.05 or P<0.01), while those of LC3-II/LC3-I, ULK1, and AMPK were significantly higher in the CS2 group (P<0.05 or P<0.01). CONCLUSION CS had a potential in treating lung injury following renal IRI through activation of the autophagy-related AMPK/mTOR signaling pathway in AKI-induced ALI.
Rats ; Male ; Animals ; AMP-Activated Protein Kinases/metabolism* ; Cordyceps/metabolism* ; Rats, Sprague-Dawley ; Kidney/pathology* ; Acute Kidney Injury/metabolism* ; Signal Transduction ; TOR Serine-Threonine Kinases/metabolism* ; Reperfusion Injury/metabolism* ; Cytokines/metabolism* ; Acute Lung Injury/drug therapy* ; Mammals/metabolism*

Acute kidney injury (AKI) is caused by a variety of diseases, which leads to acute renal function decline, azotemia, water and electrolyte disorders and acid-base balance disorders. Metabolomics is a research method that can quantitatively analyze all metabolites in an organism and find the relative relationship between metabolites and physiological and pathological changes. In recent years, several metabolites screened based on metabolomics have been proposed as potential biomarkers to assess the early development and prognosis of AKI and for the discovery of unknown potential therapeutic targets. Based on metabolomics, this paper reviews the risk prediction, early diagnosis, disease monitoring, prognosis assessment and the application of corresponding drugs for AKI, so as to provide reference for precision medicine.
Humans ; Acute Kidney Injury/metabolism* ; Metabolomics ; Prognosis ; Biomarkers ; Precision Medicine

OBJECTIVE: To evaluate the protective effect of recombinant Schistosoma japonicum cystatin (rSj-Cys) against acute kidney injury induced by acute liver failure and unravel the underlying mechanism, so as to provide insights into the clinical therapy of acute kidney injury. METHODS: Twenty-four male C57BL/6J mice at ages of 6 to 8 weeks were randomly divided into the normal control group, rSj-Cys control group, lipopolysaccharide (LPS)/D-galactosamine (D-GaIN) model group and LPS/D-GaIN + rSj-Cys treatment group, of 6 mice each group. Mice in the LPS/D-GaIN group and LPS/D-GaIN + rSj-Cys group were intraperitoneally injected with LPS (10 μg/kg) and D-GaIN (700 mg/kg), and mice in the LPS/D-GaIN + rSj-Cys group were additionally administered with rSj-Cys (1.25 mg/kg) by intraperitoneal injection 30 min post-modeling, while mice in the rSj-Cys group were intraperitoneally injected with rSj-Cys (1.25 mg/kg), and mice in the normal control group were injected with the normal volume of PBS. All mice were sacrificed 6 h post-modeling, and mouse serum and kidney samples were collected. Serum creatinine (Cr) and urea nitrogen (BUN) levels were measured, and the pathological changes of mouse kidney specimens were examined using hematoxylin-eosin (HE) staining. Serum tumor necrosis factor (TNF)-α and interleukin (IL)-6 levels were detected using enzyme-linked immunosorbent assay (ELISA), and the expression of inflammatory factors and pyroptosis-related proteins was quantified in mouse kidney specimens using immunohistochemistry. In addition, the expression of pyroptosis-related proteins and nuclear factor-kappa B (NF-κB) signaling pathway-associated proteins was determined in mouse kidney specimens using Western blotting assay. RESULTS: HE staining showed no remarkable abnormality in the mouse kidney structure in the normal control group and the rSj-Cys control group, and renal tubular injury was found in LPS/D-GaIN group, while the renal tubular injury was alleviated in LPS/D-GaIN+rSj-Cys treatment group. There were significant differences in serum levels of Cr (F = 46.33, P < 0.001), BUN (F = 128.60, P < 0.001), TNF-α (F = 102.00, P < 0.001) and IL-6 (F = 202.10, P < 0.001) among the four groups, and lower serum Cr [(85.35 ± 32.05) μmol/L], BUN [(11.90 ± 2.76) mmol/L], TNF-α [(158.27 ± 15.83) pg/mL] and IL-6 levels [(56.72 ± 4.37) pg/mL] were detected in the in LPS/D-GaIN + rSj-Cys group than in the LPS/D-GaIN group (all P values < 0.01). Immunohistochemical staining detected significant differences in TNF-α (F = 24.16, P < 0.001) and IL-10 (F = 15.07, P < 0.01) expression among the four groups, and lower TNF-α [(106.50 ± 16.57)%] and higher IL-10 expression [(91.83 ± 5.23)%] was detected in the LPS/D-GaIN + rSj-Cys group than in the LPS/D-GaIN group (both P values < 0.01). Western blotting and immunohistochemistry detected significant differences in the protein expression of pyroptosis-related proteins NOD-like receptor thermal protein domain associated protein 3 (NLRP3) (F = 24.57 and 30.72, both P values < 0.001), IL-1β (F = 19.24 and 22.59, both P values < 0.001) and IL-18 (F = 16.60 and 19.30, both P values < 0.001) in kidney samples among the four groups, and lower NLRP3, IL-1β and IL-18 expression was quantified in the LPS/D-GaIN + rSj-Cys treatment group than in the LPS/D-GaIN group (P values < 0.05). In addition, there were significant differences in the protein expression of NF-κB signaling pathway-associated proteins p-NF-κB p-P65/NF-κB p65 (F = 71.88, P < 0.001), Toll-like receptor (TLR)-4 (F = 45.49, P < 0.001) and p-IκB/IκB (F = 60.87, P < 0.001) in mouse kidney samples among the four groups, and lower expression of three NF-κB signaling pathway-associated proteins was determined in the LPS/D-GaIN + rSj-Cys treatment group than in the LPS/D-GaIN group (all P values < 0.01). CONCLUSIONS rSj-Cys may present a protective effect against acute kidney injury caused by acute liver failure through inhibiting inflammation and pyroptosis and downregulating the NF-κB signaling pathway.
Mice ; Male ; Animals ; Interleukin-10 ; Tumor Necrosis Factor-alpha/genetics* ; NF-kappa B/therapeutic use* ; Interleukin-18/therapeutic use* ; Schistosoma japonicum/metabolism* ; Interleukin-6/therapeutic use* ; Lipopolysaccharides/therapeutic use* ; NLR Family, Pyrin Domain-Containing 3 Protein ; Mice, Inbred C57BL ; Acute Kidney Injury/drug therapy* ; Liver Failure, Acute ; Cystatins/therapeutic use*

OBJECTIVES: Sufentanil has a good protective effect on myocardial and liver injury caused by ischemia reperfusion (IR), but its protective effect on kidney is still unclear. This study aims to investigate whether sufentanil can prevent IR-induced acute kidney injury (AKI) and to determine whether its efficacy is related to miR-145-mediated autophagy. METHODS: A total of 40 rats were randomly divided into 5 groups (n=8 in each group): A sham group, an IR group, a sufentanil group, a sufentanil+miR-145 inhibitor control group (an anti-NC group) and a sufentanil+miR-145 inhibitor group (an anti-miR-145 group). Except for the sham group, the other groups established a rat AKI model induced by IR. The sufentanil group, the sufentanil+anti-NC group, and the sufentanil+anti-miR-145 were injected with sufentanil (1 μg/kg) through femoral vein 30 min before ischemia. The sufentanil+anti-NC group and the sufentanil+anti-miR-145 group were injected with miR-145 inhibitor control or anti-miR-145 (80 mg/kg) through the tail vein before sufentanil pretreatment. The structure and function of kidneys harvested from the rats were evaluated, and the protein levels of autophagy-related proteins, oxidative stress levels, and apoptosis levels were measured. RESULTS: Compared with the IR group, the renal structure and function were improved in the sufentanil group. The levels of blood urea nitrogen (BUN), creatinine (Cr), urinary kidney injury molecule 1 (KIM-1), neutrophil gelatinase related lipid transporter (NGAL), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and ROS were significantly decreased (all P<0.05). In addition, compared with the IR group, the levels of Beclin-1 and LC3 in renal tissues in the sufentanil group were significantly increased (both P<0.05), and the apoptosis in renal tissues was significantly reduced (P<0.05). Compared with the sufentanil+anti-NC group, the levels of BUN, Cr, KIM-1, NGAL, TNF-α, IL-1β, IL-6 and ROS in the sufentanil+anti-miR-145 group were significantly increased (all P<0.05), the levels of Beclin-1 and LC3 in renal tissues were significantly decreased (both P<0.05), and the apoptosis in renal tissues was significantly increased (P<0.05). CONCLUSIONS Sufentanil can prevent the AKI induced by IR, which is related to the up-regulation of miR-145-mediated autophagy.
Animals ; Rats ; Acute Kidney Injury/pathology* ; Antagomirs ; Autophagy ; Beclin-1/metabolism* ; Creatinine ; Interleukin-6/metabolism* ; Ischemia ; Kidney/pathology* ; Lipocalin-2 ; MicroRNAs/metabolism* ; Reactive Oxygen Species ; Reperfusion ; Reperfusion Injury/metabolism* ; Sufentanil/therapeutic use* ; Tumor Necrosis Factor-alpha ; Up-Regulation

Acute kidney injury (AKI) refers to a clinical syndrome in which renal function declines rapidly in a short period of time caused by various pathological factors. During the development of AKI, renal tubules with the functions of reabsorption and excretion are prone to cell death due to external pathological stimuli, which is an important cause of impaired renal function. In recent years, a variety of new cell death pathways have been gradually recognized. Researchers have now found that regulated cell death (RCD), such as necroptosis, pyroptosis and ferroptosis, are important regulatory mechanisms of AKI. This article will summarize the research advances of various types of RCD involved in the process of AKI, aiming to deepen the understanding of AKI and provide innovative thoughts for the clinical treatment of AKI.
Acute Kidney Injury/metabolism* ; Cell Death ; Humans ; Kidney/metabolism* ; Necroptosis ; Necrosis/pathology* ; Regulated Cell Death

Acute kidney injury (AKI) is a common critical clinical disease characterized by a sharp decline of renal function. Ischemia-reperfusion (IR) is one of the main causes of AKI. The mortality of AKI remains high due to the lack of early diagnosis and cause specific treatment. IR rapidly initiates innate immune responses, activates complement and innate immune cells, releasing a large number of injury-related molecules such as high mobility group box-1 (HMGB1), inflammatory mediators such as caspase-3, and then recruits immune inflammatory cells including M1 macrophages (Mϕ) to the microenvironment of injury, causing apoptosis and necrosis of renal tubular epithelial cells (TECs). Dead cells and associated inflammation further activate the adaptive immune system, which not only aggravates tissue damage, but also initiates M2 Mϕ participated inflammatory clearance, tissue repair and regeneration. Mϕ, professional phagocytes, and TECs, semi-professional phagocytes, can phagocytose around damaged cells including apoptotic Mϕ and TECs, which are key innate immune cells to regulate the outcome of injury, repair or fibrosis. In recent years, it has been found that erythropoietin (EPO) not only binds to the homodimeric receptor (EPOR)₂ to induce erythropoiesis, but also binds to the heterodimeric receptor EPOR/βcR, also known as innate repair receptor, which plays renoprotective roles. Properdin is the only positive regulator in the complement activation of alternative pathway. It also can effectively identify and bind to early apoptotic T cells and facilitate phagocytic clearing by Mϕ through a non-complement activation-dependent mechanism. Our previous studies have shown that Mϕ and TECs associated with EPO and its receptors and properdin are involved in IR injury and repair, but the underlying mechanism needs to be further explored. As an important carrier of cell-to-cell signal transmission, exosomes participate in the occurrence and development of a variety of renal diseases. The role of exosomes involved in the interaction between Mϕ and TECs in IR-induced AKI is not fully defined. Based on the available results in the role of Mϕ and TECs in renal IR-induced AKI, this review discussed the role of Mϕ polarization and interaction with TECs in renal IR injury, as well as the participation of EPO and its receptors, properdin and exosomes.
Acute Kidney Injury/metabolism* ; Animals ; Epithelial Cells/metabolism* ; Humans ; Ischemia/metabolism* ; Kidney ; Macrophages/physiology* ; Mice ; Mice, Inbred C57BL ; Reperfusion ; Reperfusion Injury

Acute kidney injury (AKI) is a common clinical syndrome and an independent risk factor of chronic kidney disease and end-stage renal failure. At present, the treatments of AKI are still very limited and the morbidity and mortality of AKI are rising. Non-coding RNAs (ncRNAs), including microRNAs, long non-coding RNAs and circular RNAs (circRNAs), are RNAs that are transcribed from the genome, but not translated into proteins. It has been widely reported that ncRNA is involved in AKI caused by ischemia reperfusion injury (IRI), drugs and sepsis through different molecular biological mechanisms, such as apoptosis and oxidative stress response. Therefore, ncRNAs are expected to become a new target for clinical prevention and treatment of AKI and a new biomarker for early warning of the occurrence and prognosis of AKI. Here, the role and mechanism of ncRNA in AKI and the research progress of ncRNA as biomarkers are reviewed.
Acute Kidney Injury/metabolism* ; Humans ; MicroRNAs/metabolism* ; RNA, Circular ; RNA, Long Noncoding/genetics* ; RNA, Untranslated/genetics* ; Reperfusion Injury/genetics*